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Dr. Olga Koksharova
Belozersky Instutute of Physical-Chemical Biology, Lomonosov Moscow State University and Senior Researcher at Institute of Molecular Genetics, Russian Academy of Sciences, 119991 Moscow, Russia

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Research Keywords & Expertise

0 Photosynthesis
0 cell differentiation
0 Nitrogen Fixation
0 Cyanobacteria's genetics
0 Analyzing the structures and functions of genes responsible for cell division

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Photosynthesis
Nitrogen Fixation
cell differentiation
The formation of toxins

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Journal article
Published: 30 April 2021 in Toxins
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Non-proteinogenic neurotoxic amino acid β-N-methylamino-L-alanine (BMAA) is synthesized by cyanobacteria, diatoms, and dinoflagellates, and is known to be a causative agent of human neurodegenerative diseases. Different phytoplankton organisms’ ability to synthesize BMAA could indicate the importance of this molecule in the interactions between microalgae in nature. We were interested in the following: what kinds of mechanisms underline BMAA’s action on cyanobacterial cells in different nitrogen supply conditions. Herein, we present a proteomic analysis of filamentous cyanobacteria Nostoc sp. PCC 7120 cells that underwent BMAA treatment in diazotrophic conditions. In diazotrophic growth conditions, to survive, cyanobacteria can use only biological nitrogen fixation to obtain nitrogen for life. Note that nitrogen fixation is an energy-consuming process. In total, 1567 different proteins of Nostoc sp. PCC 7120 were identified by using LC-MS/MS spectrometry. Among them, 123 proteins belonging to different functional categories were selected—due to their notable expression differences—for further functional analysis and discussion. The presented proteomic data evidences that BMAA treatment leads to very strong (up to 80%) downregulation of α (NifD) and β (NifK) subunits of molybdenum-iron protein, which is known to be a part of nitrogenase. This enzyme is responsible for catalyzing nitrogen fixation. The genes nifD and nifK are under transcriptional control of a global nitrogen regulator NtcA. In this study, we have found that BMAA impacts in a total of 22 proteins that are under the control of NtcA. Moreover, BMAA downregulates 18 proteins that belong to photosystems I or II and light-harvesting complexes; BMAA treatment under diazotrophic conditions also downregulates five subunits of ATP synthase and enzyme NAD(P)H-quinone oxidoreductase. Therefore, we can conclude that the disbalance in energy and metabolite amounts leads to severe intracellular stress that induces the upregulation of stress-activated proteins, such as starvation-inducible DNA-binding protein, four SOS-response enzymes, and DNA repair enzymes, nine stress-response enzymes, and four proteases. The presented data provide new leads into the ecological impact of BMAA on microalgal communities that can be used in future investigations.

ACS Style

Olga Koksharova; Ivan Butenko; Olga Pobeguts; Nina Safronova; Vadim Govorun. β-N-Methylamino-L-Alanine (BMAA) Causes Severe Stress in Nostoc sp. PCC 7120 Cells under Diazotrophic Conditions: A Proteomic Study. Toxins 2021, 13, 325 .

AMA Style

Olga Koksharova, Ivan Butenko, Olga Pobeguts, Nina Safronova, Vadim Govorun. β-N-Methylamino-L-Alanine (BMAA) Causes Severe Stress in Nostoc sp. PCC 7120 Cells under Diazotrophic Conditions: A Proteomic Study. Toxins. 2021; 13 (5):325.

Chicago/Turabian Style

Olga Koksharova; Ivan Butenko; Olga Pobeguts; Nina Safronova; Vadim Govorun. 2021. "β-N-Methylamino-L-Alanine (BMAA) Causes Severe Stress in Nostoc sp. PCC 7120 Cells under Diazotrophic Conditions: A Proteomic Study." Toxins 13, no. 5: 325.

Chapter
Published: 27 August 2020 in Bacterial Volatile Compounds as Mediators of Airborne Interactions
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Cyanobacteria are photoautotrophic microorganisms; some of them are able to fix atmospheric nitrogen. They play an important role in diverse ecological systems. Cyanobacteria produce a wide variety of secondary metabolites with miscellaneous biological functions. Some of these molecules are harmful toxins that affect animals and humans health. Chemical ecology focused so far on the properties of cyanotoxins. However, this research offers important insight into the functional roles of volatile organic compounds (VOCs) and the intra- and extracellular controls of their production. Cyanobacteria are one of the main sources of VOCs, which cause disgusting odor and taste in drinking and recreational water. As far as we know, cyanobacterial volatiles have a significant impact on the physiological functions of prokaryotic and eukaryotic organisms. VOCs excreted by cyanobacteria (geosmin, 2-MIB, β-ionone, β-cyclocitral, monoterpene alcohols, aliphatic fatty acids, aliphatic alcohols, aldehydes, and others) act as allelopathic agents towards phytoplankton. Some cyanobacterial VOCs can act as both the powerful repellents and as “poor quality food” signals to grazers. These small secondary metabolites have a pronounced effect on the competition between microorganisms and hence they are ecologically very important.

ACS Style

Olga A. Koksharova. Cyanobacterial VOCs as Allelopathic Tools. Bacterial Volatile Compounds as Mediators of Airborne Interactions 2020, 257 -280.

AMA Style

Olga A. Koksharova. Cyanobacterial VOCs as Allelopathic Tools. Bacterial Volatile Compounds as Mediators of Airborne Interactions. 2020; ():257-280.

Chicago/Turabian Style

Olga A. Koksharova. 2020. "Cyanobacterial VOCs as Allelopathic Tools." Bacterial Volatile Compounds as Mediators of Airborne Interactions , no. : 257-280.

Journal article
Published: 13 August 2020 in Microorganisms
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Microbial volatile organic compounds (VOCs) are cell metabolites that affect many physiological functions of prokaryotic and eukaryotic organisms. Earlier we have demonstrated the inhibitory effects of soil bacteria volatiles, including ketones, on cyanobacteria. Cyanobacteria are very sensitive to ketone action. To investigate the possible molecular mechanisms of the ketone 2-nonanone influence on cyanobacterium Synechococcus elongatus PCC 7942, we applied a genetic approach. After Tn5-692 transposon mutagenesis, several 2-nonanone resistant mutants have been selected. Four different mutant strains were used for identification of the impaired genes (Synpcc7942_1362, Synpcc7942_0351, Synpcc7942_0732, Synpcc7942_0726) that encode correspondingly: 1) a murein-peptide ligase Mpl that is involved in the biogenesis of cyanobacteria cell wall; 2) a putative ABC transport system substrate-binding proteins MlaD, which participates in ABC transport system that maintains lipid asymmetry in the gram-negative outer membrane by aberrantly localized phospholipids transport from outer to inner membranes of bacterial cells; 3) a conserved hypothetical protein that is encoding by gene belonging to phage gene cluster in Synechococcus elongatus PCC 7942 genome; 4) a protein containing the VRR-NUC (virus-type replication-repair nuclease) domain present in restriction-modification enzymes involved in replication and DNA repair. The obtained results demonstrated that 2-nonanone may have different targets in Synechococcus elongatus PCC 7942 cells. Among them are proteins involved in the biogenesis and functioning of the cyanobacteria cell wall (Synpcc7942_1362, Synpcc7942_0351, Synpcc7942_0732) and protein participating in stress response at DNA restriction-modification level (Synpcc7942_0726). This paper is the first report about the genes that encode protein products, which can be affected by 2-nonanone.

ACS Style

Olga Koksharova; Alexandra Popova; Vladimir Plyuta; Inessa Khmel. Four New Genes of Cyanobacterium Synechococcus elongatus PCC 7942 Are Responsible for Sensitivity to 2-Nonanone. Microorganisms 2020, 8, 1234 .

AMA Style

Olga Koksharova, Alexandra Popova, Vladimir Plyuta, Inessa Khmel. Four New Genes of Cyanobacterium Synechococcus elongatus PCC 7942 Are Responsible for Sensitivity to 2-Nonanone. Microorganisms. 2020; 8 (8):1234.

Chicago/Turabian Style

Olga Koksharova; Alexandra Popova; Vladimir Plyuta; Inessa Khmel. 2020. "Four New Genes of Cyanobacterium Synechococcus elongatus PCC 7942 Are Responsible for Sensitivity to 2-Nonanone." Microorganisms 8, no. 8: 1234.

Journal article
Published: 04 June 2020 in Toxins
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All cyanobacteria produce a neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA). However, the biological function of BMAA in the regulation of cyanobacteria metabolism still remains undetermined. It is known that BMAA suppresses the formation of heterocysts in diazotrophic cyanobacteria under nitrogen starvation conditions, and BMAA induces the formation of heterocyst-like cells under nitrogen excess conditions, by causing the expression of heterocyst-specific genes that are usually “silent” under nitrogen-replete conditions, as if these bacteria receive a nitrogen deficiency intracellular molecular signal. In order to find out the molecular mechanisms underlying this unexpected BMAA effect, we studied the proteome of cyanobacterium Nostoc sp. PCC 7120 grown under BMAA treatment in nitrogen-replete medium. Experiments were performed in two experimental settings: (1) in control samples consisted of cells grown without the BMAA treatment and (2) the treated samples consisted of cells grown with addition of an aqueous solution of BMAA (20 µM). In total, 1567 different proteins of Nostoc sp. PCC 7120 were identified by LC-MS/MS spectrometry. Among them, 80 proteins belonging to different functional categories were chosen for further functional analysis and interpretation of obtained proteomic data. Here, we provide the evidence that a pleiotropic regulatory effect of BMAA on the proteome of cyanobacterium was largely different under conditions of nitrogen-excess compared to its effect under nitrogen starvation conditions (that was studied in our previous work). The most significant difference in proteome expression between the BMAA-treated and untreated samples under different growth conditions was detected in key regulatory protein PII (GlnB). BMAA downregulates protein PII in nitrogen-starved cells and upregulates this protein in nitrogen-replete conditions. PII protein is a key signal transduction protein and the change in its regulation leads to the change of many other regulatory proteins, including different transcriptional factors, enzymes and transporters. Complex changes in key metabolic and regulatory proteins (RbcL, RbcS, Rca, CmpA, GltS, NodM, thioredoxin 1, RpbD, ClpP, MinD, RecA, etc.), detected in this experimental study, could be a reason for the appearance of the “starvation” state in nitrogen-replete conditions in the presence of BMAA. In addition, 15 proteins identified in this study are encoded by genes, which are under the control of NtcA—a global transcriptional regulator—one of the main protein partners and transcriptional regulators of PII protein. Thereby, this proteomic study gives a possible explanation of cyanobacterium starvation under nitrogen-replete conditions and BMAA treatment. It allows to take a closer look at the regulation of cyanobacteria metabolism affected by this cyanotoxin.

ACS Style

Olga A. Koksharova; Ivan O. Butenko; Olga V. Pobeguts; Nina A. Safronova; Vadim M. Govorun. Proteomic Insights into Starvation of Nitrogen-Replete Cells of Nostoc sp. PCC 7120 under β-N-Methylamino-L-Alanine (BMAA) Treatment. Toxins 2020, 12, 372 .

AMA Style

Olga A. Koksharova, Ivan O. Butenko, Olga V. Pobeguts, Nina A. Safronova, Vadim M. Govorun. Proteomic Insights into Starvation of Nitrogen-Replete Cells of Nostoc sp. PCC 7120 under β-N-Methylamino-L-Alanine (BMAA) Treatment. Toxins. 2020; 12 (6):372.

Chicago/Turabian Style

Olga A. Koksharova; Ivan O. Butenko; Olga V. Pobeguts; Nina A. Safronova; Vadim M. Govorun. 2020. "Proteomic Insights into Starvation of Nitrogen-Replete Cells of Nostoc sp. PCC 7120 under β-N-Methylamino-L-Alanine (BMAA) Treatment." Toxins 12, no. 6: 372.

Journal article
Published: 09 May 2020 in Toxins
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The oldest prokaryotic photoautotrophic organisms, cyanobacteria, produce many different metabolites. Among them is the water-soluble neurotoxic non-protein amino acid beta-N-methylamino-L-alanine (BMAA), whose biological functions in cyanobacterial metabolism are of fundamental scientific and practical interest. An early BMAA inhibitory effect on nitrogen fixation and heterocyst differentiation was shown in strains of diazotrophic cyanobacteria Nostoc sp. PCC 7120, Nostoc punctiforme PCC 73102 (ATCC 29133), and Nostoc sp. strain 8963 under conditions of nitrogen starvation. Herein, we present a comprehensive proteomic study of Nostoc (also called Anabaena) sp. PCC 7120 in the heterocyst formation stage affecting by BMAA treatment under nitrogen starvation conditions. BMAA disturbs proteins involved in nitrogen and carbon metabolic pathways, which are tightly co-regulated in cyanobacteria cells. The presented evidence shows that exogenous BMAA affects a key nitrogen regulatory protein, PII (GlnB), and some of its protein partners, as well as glutamyl-tRNA synthetase gltX and other proteins that are involved in protein synthesis, heterocyst differentiation, and nitrogen metabolism. By taking into account the important regulatory role of PII, it becomes clear that BMAA has a severe negative impact on the carbon and nitrogen metabolism of starving Nostoc sp. PCC 7120 cells. BMAA disturbs carbon fixation and the carbon dioxide concentrating mechanism, photosynthesis, and amino acid metabolism. Stress response proteins and DNA repair enzymes are upregulated in the presence of BMAA, clearly indicating severe intracellular stress. This is the first proteomic study of the effects of BMAA on diazotrophic starving cyanobacteria cells, allowing a deeper insight into the regulation of the intracellular metabolism of cyanobacteria by this non-protein amino acid.

ACS Style

Olga A. Koksharova; Ivan O. Butenko; Olga V. Pobeguts; Nina A. Safronova; Vadim M. Govorun. The First Proteomic Study of Nostoc sp. PCC 7120 Exposed to Cyanotoxin BMAA under Nitrogen Starvation. Toxins 2020, 12, 310 .

AMA Style

Olga A. Koksharova, Ivan O. Butenko, Olga V. Pobeguts, Nina A. Safronova, Vadim M. Govorun. The First Proteomic Study of Nostoc sp. PCC 7120 Exposed to Cyanotoxin BMAA under Nitrogen Starvation. Toxins. 2020; 12 (5):310.

Chicago/Turabian Style

Olga A. Koksharova; Ivan O. Butenko; Olga V. Pobeguts; Nina A. Safronova; Vadim M. Govorun. 2020. "The First Proteomic Study of Nostoc sp. PCC 7120 Exposed to Cyanotoxin BMAA under Nitrogen Starvation." Toxins 12, no. 5: 310.

Journal article
Published: 01 January 2020 in Russian Journal of Plant Physiology
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Filamentous cyanobacteria belong to the oldest organisms on our planet. Many cyanobacteria exist in the form of trichomes, i.e., cell chains comprising hundreds of cells connected by intercellular interactions. Under deficiency of environmental nitrogen, the cells in trichomes of some cyanobacteria undergo specialization to perform separate functions of oxygenic photosynthesis and nitrogen fixation. Thus, the trichome transforms into a complex organism (complex system), in which vegetative cells and the heterocysts exchange with photosynthetic and nitrogen fixation products. The transmission of metabolites may proceed via the periplasmic space or through the special contact structures called microplasmodesmata, septosomes, septal contacts, or nanopores. In filamentous cyanobacteria, the storage and transmission of energy at the cellular level is accompanied by electrical processes occurring in cell membranes. Theoretical and model analysis of extracellular currents induced by the local illumination in trichomes of Phormidium uncinatum showed that the trichomes are cell associations organized into unified cables capable of transferring energy along the trichome. From the viewpoint of modern molecular genetics, filamentous cyanobacteria showing the distribution of functions between neighboring cells are the prototype of a multicellular organism and a convenient model for elucidating the regulatory mechanisms of multicellularity, which, apparently, appeared more than once during the evolution in different phylogenetic groups, including bacteria, fungi, algae, and plants.

ACS Style

T. V. Potapova; O. A. Koksharova. Filamentous Cyanobacteria as a Prototype of Multicellular Organisms. Russian Journal of Plant Physiology 2020, 67, 17 -30.

AMA Style

T. V. Potapova, O. A. Koksharova. Filamentous Cyanobacteria as a Prototype of Multicellular Organisms. Russian Journal of Plant Physiology. 2020; 67 (1):17-30.

Chicago/Turabian Style

T. V. Potapova; O. A. Koksharova. 2020. "Filamentous Cyanobacteria as a Prototype of Multicellular Organisms." Russian Journal of Plant Physiology 67, no. 1: 17-30.

Research article
Published: 12 December 2019 in BioMed Research International
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In this study, we investigated the quorum sensing (QS) regulatory system of the psychrotrophic strainSerratia proteamaculans94 isolated from spoiled refrigerated meat. The strain produced severalN-acyl-L-homoserine-lactone (AHL) QS signal molecules, withN-(3-oxo-hexanoyl)-L-homoserine lactone andN-(3-hydroxy-hexanoyl)-L-homoserine lactone as two main types. ThesprIandsprRgenes encoding an AHL synthase and a receptor regulatory protein, respectively, were cloned and sequenced. Analysis of their nucleotide sequence showed that these genes were transcribed convergently and that their reading frames partly overlapped by 23 bp in the terminal regions. The genes were highly similar to theluxI/luxR-type QS genes of other Gram-negative bacteria. Anspr-box (analog of thelux-box) was identified upstream of thesprRgene and found to be overlapped with the sequence of −10 sequence site in the promoter region of this gene. Inactivation of thesprIgene led to the absence of AHL synthesis, chitinolytic activity, and swimming motility; decrease of extracellular proteolytic activity; affected the cellular fatty acid composition; and reduced suppression of the fungal plant pathogen mycelium growth by volatile compounds emitted by strainS. proteamaculans94. The data obtained demonstrated the important role of the QS system in the regulation of cellular processes inS. proteamaculans94.

ACS Style

Yulia V. Zaitseva; Olga A. Koksharova; Valentina A. Lipasova; Vladimir A. Plyuta; Ilya V. Demidyuk; Leonid S. Chernin; Inessa A. Khmel. SprI/SprR Quorum Sensing System ofSerratia proteamaculans94. BioMed Research International 2019, 2019, 1 -10.

AMA Style

Yulia V. Zaitseva, Olga A. Koksharova, Valentina A. Lipasova, Vladimir A. Plyuta, Ilya V. Demidyuk, Leonid S. Chernin, Inessa A. Khmel. SprI/SprR Quorum Sensing System ofSerratia proteamaculans94. BioMed Research International. 2019; 2019 ():1-10.

Chicago/Turabian Style

Yulia V. Zaitseva; Olga A. Koksharova; Valentina A. Lipasova; Vladimir A. Plyuta; Ilya V. Demidyuk; Leonid S. Chernin; Inessa A. Khmel. 2019. "SprI/SprR Quorum Sensing System ofSerratia proteamaculans94." BioMed Research International 2019, no. : 1-10.

Regular article
Published: 26 March 2019 in Journal of Phycology
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Microbial volatiles have a significant impact on the physiological functions of prokaryotic and eukaryotic organisms. Various ketones are present in volatile mixtures produced by plants, bacteria, and fungi. Our earlier results demonstrated the inhibitory effects of soil bacteria volatiles, including ketones, on cyanobacteria. In this work, we thoroughly examined the natural ketones 2‐nonanone and 2‐undecanone to determine their influence on the photosynthetic activity in Synechococcus sp. PCC 7942. We observed for the first time that the ketones strongly inhibit electron transport through PSII in cyanobacteria cells in vivo. The addition of ketones decreases the quantum yield of primary PSII photoreactions and changes the PSII chlorophyll fluorescence induction curves. There are clear indications that the ketones inhibit electron transfer from QA to QB, electron transport at the donor side of PSII. The ketones can also modify the process of energy transfer from the antenna complex to the PSII reaction center and, by this means, increase both chlorophyll fluorescence quantum yield and the chlorophyll excited state lifetime. At the highest tested concentration (5 mM) 2‐nonanone also induced chlorophyll release from Synechococcus cells that strongly indicates the possible role of the ketones as detergents. This article is protected by copyright. All rights reserved.

ACS Style

Elena N. Voronova; Ivan Konyukhov; Olga A. Koksharova; Alexandra A. Popova; Sergey I. Pogosyan; Inessa A. Khmel; Andrey B. Rubin. Inhibition of cyanobacterial photosynthetic activity by natural ketones. Journal of Phycology 2019, 55, 840 -857.

AMA Style

Elena N. Voronova, Ivan Konyukhov, Olga A. Koksharova, Alexandra A. Popova, Sergey I. Pogosyan, Inessa A. Khmel, Andrey B. Rubin. Inhibition of cyanobacterial photosynthetic activity by natural ketones. Journal of Phycology. 2019; 55 (4):840-857.

Chicago/Turabian Style

Elena N. Voronova; Ivan Konyukhov; Olga A. Koksharova; Alexandra A. Popova; Sergey I. Pogosyan; Inessa A. Khmel; Andrey B. Rubin. 2019. "Inhibition of cyanobacterial photosynthetic activity by natural ketones." Journal of Phycology 55, no. 4: 840-857.

Journal article
Published: 06 February 2019 in Nanomaterials
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In the present work, we provide evidence for visible light irradiation of the Au/TiO2 nanoparticles’ surface plasmon resonance band (SPR) leading to electron injection from the Au nanoparticles to the conduction band of TiO2. The Au/TiO2 SPR band is shown to greatly enhance the light absorption of TiO2 in the visible region. Evidence is presented for the light absorption by the Au/TiO2 plasmon bands leading to the dissolution of Au nanoparticles. This dissolution occurs concomitantly with the injection of the hot electrons generated by the Au plasmon into the conduction band of TiO2. The electron injection from the Au nanoparticles into TiO2 was followed by femtosecond spectroscopy. The formation of Au ions was further confirmed by the spectral shift of the transient absorption spectra of Au/TiO2. The spectral changes of the SPR band of Au/TiO2 nanoparticles induced by visible light were detected by spectrophotometer, and the morphological transformation of Au/TiO2 was revealed by electron microscopy techniques as well. Subsequently, the fate of the Au ions was sorted out during the growth and biofilm formation for some selected Gram-negative bacteria. This study compares the bactericidal mechanism of Au ions and Ag ions, which were found to be substantially different depending on the selected cell used as a probe.

ACS Style

Marina Radzig; Olga Koksharova; Inessa Khmel; Vladimir Ivanov; Khursand Yorov; John Kiwi; Sami Rtimi; Elina Tastekova; Arseny Aybush; Victor Nadtochenko. Femtosecond Spectroscopy of Au Hot-Electron Injection into TiO2: Evidence for Au/TiO2 Plasmon Photocatalysis by Bactericidal Au Ions and Related Phenomena. Nanomaterials 2019, 9, 217 .

AMA Style

Marina Radzig, Olga Koksharova, Inessa Khmel, Vladimir Ivanov, Khursand Yorov, John Kiwi, Sami Rtimi, Elina Tastekova, Arseny Aybush, Victor Nadtochenko. Femtosecond Spectroscopy of Au Hot-Electron Injection into TiO2: Evidence for Au/TiO2 Plasmon Photocatalysis by Bactericidal Au Ions and Related Phenomena. Nanomaterials. 2019; 9 (2):217.

Chicago/Turabian Style

Marina Radzig; Olga Koksharova; Inessa Khmel; Vladimir Ivanov; Khursand Yorov; John Kiwi; Sami Rtimi; Elina Tastekova; Arseny Aybush; Victor Nadtochenko. 2019. "Femtosecond Spectroscopy of Au Hot-Electron Injection into TiO2: Evidence for Au/TiO2 Plasmon Photocatalysis by Bactericidal Au Ions and Related Phenomena." Nanomaterials 9, no. 2: 217.

Journal article
Published: 16 November 2018 in Toxins
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Cyanobacteria synthesize neurotoxic β-N-methylamino-l-alanine (BMAA). The roles of this non-protein amino acid in cyanobacterial cells are insufficiently studied. During diazotrophic growth, filamentous cyanobacteria form single differentiated cells, called heterocysts, which are separated by approximately 12–15 vegetative cells. When combined nitrogen is available, heterocyst formation is blocked and cyanobacterial filaments contain only vegetative cells. In the present study, we discovered that exogenous BMAA induces the process of heterocyst formation in filamentous cyanobacteria under nitrogen-replete conditions that normally repress cell differentiation. BMAA treated cyanobacteria form heterocyst-like dark non-fluorescent non-functional cells. It was found that glutamate eliminates the BMAA mediated derepression. Quantitative polymerase chain reaction (qPCR) permitted to detect the BMAA impact on the transcriptional activity of several genes that are implicated in nitrogen assimilation and heterocyst formation in Anabaena sp. PCC 7120. We demonstrated that the expression of several essential genes increases in the BMAA presence under repressive conditions.

ACS Style

Alexandra A. Popova; Tatiana A. Semashko; Natalia V. Kostina; Ulla Rasmussen; Vadim M. Govorun; Olga A. Koksharova. The Cyanotoxin BMAA Induces Heterocyst Specific Gene Expression in Anabaena sp. PCC 7120 under Repressive Conditions. Toxins 2018, 10, 478 .

AMA Style

Alexandra A. Popova, Tatiana A. Semashko, Natalia V. Kostina, Ulla Rasmussen, Vadim M. Govorun, Olga A. Koksharova. The Cyanotoxin BMAA Induces Heterocyst Specific Gene Expression in Anabaena sp. PCC 7120 under Repressive Conditions. Toxins. 2018; 10 (11):478.

Chicago/Turabian Style

Alexandra A. Popova; Tatiana A. Semashko; Natalia V. Kostina; Ulla Rasmussen; Vadim M. Govorun; Olga A. Koksharova. 2018. "The Cyanotoxin BMAA Induces Heterocyst Specific Gene Expression in Anabaena sp. PCC 7120 under Repressive Conditions." Toxins 10, no. 11: 478.

Original article
Published: 25 October 2018 in Folia Microbiologica
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The luxS gene is responsible for the synthesis of AI-2 (autoinducer-2), a signaling molecule that participates in quorum sensing regulation in a large number of bacteria. In this work, we investigated which phenotypes are regulated by luxS gene in Serratia proteamaculans 94, psychrotrophic strain isolated from spoiled refrigerated meat. AI-2 was identified in S. proteamaculans 94, and the luxS gene involved in its synthesis was cloned and sequenced. A mutant with the inactivated luxS gene was constructed. Inactivation of the luxS gene was shown to lead to the absence of AI-2 synthesis, chitinolytic activity, swimming motility, suppression of the growth of fungal plant pathogens Rhizoctonia solani and Helminthosporium sativum by volatile compounds emitted by S. proteamaculans 94 strain, and to a decrease of extracellular proteolytic activity. The knockout of the luxS gene did not affect synthesis of N-acyl-homoserine lactones, lipolytic, and hemolytic activities of S. proteamaculans 94.

ACS Style

Yu. V. Zaitseva; V. A. Lipasova; V. A. Plyuta; O. A. Koksharova; I. V. Demidyuk; S. V. Kostrov; I. A. Khmel. Effect of inactivation of luxS gene on the properties of Serratia proteamaculans 94 strain. Folia Microbiologica 2018, 64, 265 -272.

AMA Style

Yu. V. Zaitseva, V. A. Lipasova, V. A. Plyuta, O. A. Koksharova, I. V. Demidyuk, S. V. Kostrov, I. A. Khmel. Effect of inactivation of luxS gene on the properties of Serratia proteamaculans 94 strain. Folia Microbiologica. 2018; 64 (3):265-272.

Chicago/Turabian Style

Yu. V. Zaitseva; V. A. Lipasova; V. A. Plyuta; O. A. Koksharova; I. V. Demidyuk; S. V. Kostrov; I. A. Khmel. 2018. "Effect of inactivation of luxS gene on the properties of Serratia proteamaculans 94 strain." Folia Microbiologica 64, no. 3: 265-272.

Journal article
Published: 01 July 2018 in Nanotechnologies in Russia
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The aim of this work is to study the possibility of removing antimicrobial peptides arenicin-1 and tachyplesin-1 from aqueous solutions using new highly hydrophobic nanomaterials—carbon nanotubes (CNTs) Taunit-M. Two types of CNTs, respectively, functionalized and nonfunctionalized with–COOH groups are studied. The RP HPLC method is used for the quantification of peptides in solutions before and after the sorption on the CNTs. It is revealed that tachyplesin-1 and arenicin-1 are actually not adsorbed on nonfunctionalized CNTs. A theoretical calculation of specific hydrophobicity and aliphatic index shows that both peptides have poorly expressed hydrophobic properties, and this can explain lack of their adsorption. On the contrary, using functionalized CNTs makes it possible to remove up to 89% of arenicin-1 and 92% of tachyplesin-1 from the solution. A comparative study of adsorption of the antimicrobial peptide tachyplesin- 1 on nonfunctionalized activated carbons and functionalized CNTs shows that the amount of peptide adsorbed on activated carbons is about three times less than that absorbed on CNTs. It is assumed that the high adsorption capacity of the functionalized CNTs toward the studied peptides results from the functionalization of the sorbent surface with the–COOH groups capable of forming ionic bonds with free–NH2 groups of peptides. This shows the prospects for using functionalized CNTs as sorbents for the removal of toxic preparations of peptide origin from aqueous solutions.

ACS Style

A. V. Timofeeva; Alexander Ksenofontov; O. A. Koksharova. Removal of Antimicrobial Peptides from Aqueous Solutions Using Carbon Nanotubes. Nanotechnologies in Russia 2018, 13, 443 -447.

AMA Style

A. V. Timofeeva, Alexander Ksenofontov, O. A. Koksharova. Removal of Antimicrobial Peptides from Aqueous Solutions Using Carbon Nanotubes. Nanotechnologies in Russia. 2018; 13 (7-8):443-447.

Chicago/Turabian Style

A. V. Timofeeva; Alexander Ksenofontov; O. A. Koksharova. 2018. "Removal of Antimicrobial Peptides from Aqueous Solutions Using Carbon Nanotubes." Nanotechnologies in Russia 13, no. 7-8: 443-447.

Journal article
Published: 06 May 2018 in Environmental Microbiology Reports
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Various species of cyanobacteria, diatoms and dinoflagellates are capable of synthesizing the non-proteinogenic neurotoxic amino acid β-N-methylamino-L-alanine (BMAA), which is known to be a causative agent of human neurodegeneration. Similar to most cyanotoxins, the biological and ecological functions of BMAA in cyanobacteria are unknown. In this study, we show for the first time that BMAA, in micromolar amounts, inhibits the formation of heterocysts (specialized nitrogen-fixing cells) in heterocystous, diazotrophic cyanobacteria (Anabaena sp. PCC 7120, Nostoc punctiforme PCC 73102 (ATCC 29133), Nostoc sp. strain 8963) under conditions of nitrogen starvation. The inhibitory effect of BMAA is abolished by the addition of glutamate. To understand the genetic reason for the observed phenomenon, we used qPCR to study the expression of key genes involved in cell differentiation and nitrogen metabolism in the model cyanobacterium Anabaena sp. PCC 7120. We observed that in the presence of BMAA, Anabaena sp. PCC 7120 does not express two essential genes associated with heterocyst differentiation, namely, hetR and hepA. We also found that addition of BMAA to cyanobacterial cultures with mature heterocysts inhibits nifH gene expression and nitrogenase activity. This article is protected by copyright. All rights reserved.

ACS Style

Alexandra A. Popova; Ulla Rasmussen; Tatiana A. Semashko; Vadim M. Govorun; Olga A. Koksharova. Stress effects of cyanotoxin β-methylamino-L-alanine (BMAA) on cyanobacterial heterocyst formation and functionality. Environmental Microbiology Reports 2018, 10, 369 -377.

AMA Style

Alexandra A. Popova, Ulla Rasmussen, Tatiana A. Semashko, Vadim M. Govorun, Olga A. Koksharova. Stress effects of cyanotoxin β-methylamino-L-alanine (BMAA) on cyanobacterial heterocyst formation and functionality. Environmental Microbiology Reports. 2018; 10 (3):369-377.

Chicago/Turabian Style

Alexandra A. Popova; Ulla Rasmussen; Tatiana A. Semashko; Vadim M. Govorun; Olga A. Koksharova. 2018. "Stress effects of cyanotoxin β-methylamino-L-alanine (BMAA) on cyanobacterial heterocyst formation and functionality." Environmental Microbiology Reports 10, no. 3: 369-377.

Journal article
Published: 15 October 2017 in Russian Journal of Plant Physiology
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Cyanobacteria are photoautotrophic bacteria that are known also as blue-green algae. They accumulate on different surfaces and objects and contribute to their biodegradation. Moreover, cyanobacteria produce toxins, which lead to harmful environmental and human health impacts. Hence, cyanobacterial growth control problem is very vital. The goal of the study was to obtain new nanocomplexes on the basis of a modern nanomaterial Taunit associated with antibiotic chloramphenicol and herbicide diuron and to test their antimicrobial effect against a model organism such as the unicellular cyanobacterium Synechocystis sp. PCC 6803. A nanomaterial made of multiwalled carbon nanotubes (MWCNTs) called Taunit was used for the first time to obtain nanocomplexes coupled either with herbicide diuron (DCMU (3-(3,4-dichlorophenyl)- 1,1-dimethylurea) or with antibiotic chloramphenicol. A small amount of Taunit (~1 mg) was needed to adsorb micrograms of diuron or chloramphenicol. The new formed nanocomplexes differentiate in their antimicrobial activity, which could be explained by the difference in their chemical mechanism of action. Taunit − diuron complex showed a higher biocide action against cyanobacterium than the Taunit − chloramphenicol complex. The results allow to discuss the prospects of research on the use of Taunit − diuron complex as a coating for various surfaces exposed to cyanobacteria fouling.

ACS Style

A. V. Timofeeva; V. N. Tashlitsky; A. G. Tkachev; L. A. Baratova; O. A. Koksharova. Nanocomplexes on the basis of Taunit associated with biocides as effective anti-cyanobacterial agents. Russian Journal of Plant Physiology 2017, 64, 833 -838.

AMA Style

A. V. Timofeeva, V. N. Tashlitsky, A. G. Tkachev, L. A. Baratova, O. A. Koksharova. Nanocomplexes on the basis of Taunit associated with biocides as effective anti-cyanobacterial agents. Russian Journal of Plant Physiology. 2017; 64 (6):833-838.

Chicago/Turabian Style

A. V. Timofeeva; V. N. Tashlitsky; A. G. Tkachev; L. A. Baratova; O. A. Koksharova. 2017. "Nanocomplexes on the basis of Taunit associated with biocides as effective anti-cyanobacterial agents." Russian Journal of Plant Physiology 64, no. 6: 833-838.

Review
Published: 10 August 2016 in Biochemistry (Moscow)
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Secondary metabolites of photoautotrophic organisms have attracted considerable interest in recent years. In particular, molecules of non-proteinogenic amino acids participating in various physiological processes and capable of producing adverse ecological effects have been actively investigated. For example, the non-proteinogenic amino acid β-N-methylamino-L-alanine (BMAA) is neurotoxic to animals including humans. It is known that BMAA accumulation via the food chain can lead to development of neurodegenerative diseases in humans such as Alzheimer's and Parkinson's diseases as well as amyotrophic lateral sclerosis. Moreover, BMAA can be mistakenly incorporated into a protein molecule instead of serine. Natural sources of BMAA and methods for its detection are discussed in this review, as well as the role of BMAA in metabolism of its producers and possible mechanisms of toxicity of this amino acid in different living organisms.

ACS Style

A. A. Popova; O. A. Koksharova. Neurotoxic non-proteinogenic amino acid β-N-methylamino-L-alanine and its role in biological systems. Biochemistry (Moscow) 2016, 81, 794 -805.

AMA Style

A. A. Popova, O. A. Koksharova. Neurotoxic non-proteinogenic amino acid β-N-methylamino-L-alanine and its role in biological systems. Biochemistry (Moscow). 2016; 81 (8):794-805.

Chicago/Turabian Style

A. A. Popova; O. A. Koksharova. 2016. "Neurotoxic non-proteinogenic amino acid β-N-methylamino-L-alanine and its role in biological systems." Biochemistry (Moscow) 81, no. 8: 794-805.

English abstract
Published: 16 June 2016 in Микробиология
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ACS Style

M A Radtsig; O A Koksharova; V A Nadtochenko; I A Khmel. [Production of Gold Nanoparticles by Biogenesis Using Bacteria]. Микробиология 2016, 85, 1 .

AMA Style

M A Radtsig, O A Koksharova, V A Nadtochenko, I A Khmel. [Production of Gold Nanoparticles by Biogenesis Using Bacteria]. Микробиология. 2016; 85 (1):1.

Chicago/Turabian Style

M A Radtsig; O A Koksharova; V A Nadtochenko; I A Khmel. 2016. "[Production of Gold Nanoparticles by Biogenesis Using Bacteria]." Микробиология 85, no. 1: 1.

Journal article
Published: 23 May 2016 in APMIS
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The ability to form biofilms plays an important role in bacteria-host interactions, including plant pathogenicity. In this work, we investigated the action of volatile organic compounds (VOCs) produced by rhizospheric strains of Pseudomonas chlororaphis 449, Pseudomonas fluorescens B-4117, Serratia plymuthica IC1270, as well as Serratia proteamaculans strain 94, isolated from spoiled meat, on biofilms formation by three strains of Agrobacterium tumefaciens which are causative agents of crown-gall disease in a wide range of plants. In dual culture assays, the pool of volatiles emitted by the tested Pseudomonas and Serratia strains suppressed the formation of biofilms of A. tumefaciens strains grown on polycarbonate membrane filters and killed Agrobacterium cells in mature biofilms. The individual VOCs produced by the tested Pseudomonas strains, that is, ketones (2-nonanone, 2-heptanone, 2-undecanone), and dimethyl disulfide (DMDS) produced by Serratia strains, were shown to kill A. tumefaciens cells in mature biofilms and suppress their formation. The data obtained in this study suggest an additional potential of some ketones and DMDS as protectors of plants against A. tumefaciens strains, whose virulence is associated with the formation of biofilms on the infected plants.

ACS Style

Vladimir Plyuta; Valentina Lipasova; Alexandra Popova; Olga Koksharova; Alexander Kuznetsov; Erno Szegedi; Leonid Chernin; Inessa Khmel. Influence of volatile organic compounds emitted byPseudomonasandSerratiastrains onAgrobacterium tumefaciensbiofilms. APMIS 2016, 124, 586 -594.

AMA Style

Vladimir Plyuta, Valentina Lipasova, Alexandra Popova, Olga Koksharova, Alexander Kuznetsov, Erno Szegedi, Leonid Chernin, Inessa Khmel. Influence of volatile organic compounds emitted byPseudomonasandSerratiastrains onAgrobacterium tumefaciensbiofilms. APMIS. 2016; 124 (7):586-594.

Chicago/Turabian Style

Vladimir Plyuta; Valentina Lipasova; Alexandra Popova; Olga Koksharova; Alexander Kuznetsov; Erno Szegedi; Leonid Chernin; Inessa Khmel. 2016. "Influence of volatile organic compounds emitted byPseudomonasandSerratiastrains onAgrobacterium tumefaciensbiofilms." APMIS 124, no. 7: 586-594.

Journal article
Published: 01 May 2016 in Nanotechnologies in Russia
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Cyanobacteria Anabaena sp. PCC 7120 have been analyzed by time-of-flight secondary ion mass spectrometry and two-photon luminescence microscopy. The reduction of Ag+ ions to silver nanoparticles inside the cells is detected. The silver ion signal is shown to be much greater inside certain cells. Comparing the distribution of Ag ions with optical images allows us to identify these cells as heterocysts, which are specialized nitrogen-fixing cells.

ACS Style

A. A. Gulin; O. A. Koksharova; A. A. Popova; I. A. Khmel’; A. A. Astaf’Ev; Aleksander Shakhov; V. A. Nadtochenko. Visualization of the spatial distribution of Ag ions in cyanobacteria Anabaena sp. PCC 7120 by time-of-flight secondary ion mass spectrometry and two-photon luminescence microscopy. Nanotechnologies in Russia 2016, 11, 361 -363.

AMA Style

A. A. Gulin, O. A. Koksharova, A. A. Popova, I. A. Khmel’, A. A. Astaf’Ev, Aleksander Shakhov, V. A. Nadtochenko. Visualization of the spatial distribution of Ag ions in cyanobacteria Anabaena sp. PCC 7120 by time-of-flight secondary ion mass spectrometry and two-photon luminescence microscopy. Nanotechnologies in Russia. 2016; 11 (5):361-363.

Chicago/Turabian Style

A. A. Gulin; O. A. Koksharova; A. A. Popova; I. A. Khmel’; A. A. Astaf’Ev; Aleksander Shakhov; V. A. Nadtochenko. 2016. "Visualization of the spatial distribution of Ag ions in cyanobacteria Anabaena sp. PCC 7120 by time-of-flight secondary ion mass spectrometry and two-photon luminescence microscopy." Nanotechnologies in Russia 11, no. 5: 361-363.

Journal article
Published: 01 May 2016 in Microbiological Research
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In order to study the regulation of N-acyl-homoserine lactones synthesis (AHLs, the signal molecules of Quorum Sensing regulation) in Burkholderia cenocepacia strain 370 we obtained mutants with increased AHL production. One of the mutants, named BC-B6, was obtained by TnMod-RKmr plasposon mutagenesis. The plasposon insertion was located within the clpX gene encoding the ATPase subunit ClpX of the ClpXP protease. The mutation reduced bacterial virulence in mice intranasal infection. The results of proteomic analysis demonstrated that the expression of at least 19 proteins differed not less than 2-fold between the parental and mutant strains. 18 of the proteins were upregulated in the mutant, and one protein was downregulated. The proteins included those that involved in protein synthesis and modification, in energy production, in general metabolism, in transport and regulation. To check the effect of the clpX mutation on the AHL synthesis, a mutant with inactivated clpX gene (BC-clpX:Kmr) was constructed by gene replacement method. This mutant also exhibited increased AHLs production. A swarming motility of both mutants was reduced compared to the original strain. Thus, the obtained results show that the clpX gene was involved in the regulation of AHL production and a number of cellular processes in B. cenocepacia 370.

ACS Style

M.A. Veselova; Yu. M. Romanova; V.A. Lipasova; O.A. Koksharova; Yu. V. Zaitseva; M.U. Chernukha; Alexander Gintsburg; I.A. Khmel. The effect of mutation in the clp X gene on the synthesis of N -acyl-homoserine lactones and other properties of Burkholderia cenocepacia 370. Microbiological Research 2016, 186-187, 90 -98.

AMA Style

M.A. Veselova, Yu. M. Romanova, V.A. Lipasova, O.A. Koksharova, Yu. V. Zaitseva, M.U. Chernukha, Alexander Gintsburg, I.A. Khmel. The effect of mutation in the clp X gene on the synthesis of N -acyl-homoserine lactones and other properties of Burkholderia cenocepacia 370. Microbiological Research. 2016; 186-187 ():90-98.

Chicago/Turabian Style

M.A. Veselova; Yu. M. Romanova; V.A. Lipasova; O.A. Koksharova; Yu. V. Zaitseva; M.U. Chernukha; Alexander Gintsburg; I.A. Khmel. 2016. "The effect of mutation in the clp X gene on the synthesis of N -acyl-homoserine lactones and other properties of Burkholderia cenocepacia 370." Microbiological Research 186-187, no. : 90-98.

Journal article
Published: 01 January 2016 in Микробиология
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ACS Style

М. А. Радциг; И. А. Хмель; M. A. Radtsig; O. A. Koksharova; V. A. Nadtochenko; I. A. Khmel’. Получение наночастиц золота методом биогенеза с использованием бактерий. Микробиология 2016, 85, 42 -49.

AMA Style

М. А. Радциг, И. А. Хмель, M. A. Radtsig, O. A. Koksharova, V. A. Nadtochenko, I. A. Khmel’. Получение наночастиц золота методом биогенеза с использованием бактерий. Микробиология. 2016; 85 (1):42-49.

Chicago/Turabian Style

М. А. Радциг; И. А. Хмель; M. A. Radtsig; O. A. Koksharova; V. A. Nadtochenko; I. A. Khmel’. 2016. "Получение наночастиц золота методом биогенеза с использованием бактерий." Микробиология 85, no. 1: 42-49.