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Patricia Hernández Martinez
Universitat de Valencia, Burjassot, Spain

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Research article
Published: 15 June 2021 in Biochemical Journal
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The ABC transporters are membrane proteins that can act as putative receptors for Cry proteins from Bacillus thuringiensis (Bt) in the midgut of different insects. For the beet armyworm, Spodoptera exigua, ABCC2 and ABCC3 have been found to interact with Cry1A proteins, the main insecticidal proteins used in Bt-crops, as well as Bt-based pesticides. The ABCC2 has shown to have specific binding towards Cry1Ac and is involved in the toxic process of Cry1A proteins, but the role of this transporter and how it relates with the Cry1A proteins is still unknown. Here, we have characterized the interactions between the SeABCC2 and the main proteins that bind to the receptor. By labelling the Cry1Aa protein, we have found that virtually all of the binding is in an oligomeric state, a conformation that allowed higher levels of specific binding that could not be achieved by the monomeric protein on its own. Furthermore, we have observed that Cry1A proteins can hetero-oligomerize in the presence of the transporter, which is reflected in an increase in binding and toxicity to SeABCC2-expressing cells. This synergism can be one of the reasons why B. thuringiensis co-expresses different Cry1 proteins that can apparently have similar binding preferences. The results from in vitro competition and ex vivo competition showed that Cry1Aa, Cry1Ab and Cry1Ac share functional binding sites. By using Cry1Ab-Cry1Ac chimeras, the presence of domain I from Cry1A proteins was revealed to be critical for oligomer formation.

ACS Style

Daniel Pinos; Noelia Joya; Salvador Herrero; Juan Ferré; Patricia Hernández Martinez. Hetero-oligomerization of Bacillus thuringiensis Cry1A proteins enhance binding to the ABCC2 transporter of Spodoptera exigua. Biochemical Journal 2021, 1 .

AMA Style

Daniel Pinos, Noelia Joya, Salvador Herrero, Juan Ferré, Patricia Hernández Martinez. Hetero-oligomerization of Bacillus thuringiensis Cry1A proteins enhance binding to the ABCC2 transporter of Spodoptera exigua. Biochemical Journal. 2021; ():1.

Chicago/Turabian Style

Daniel Pinos; Noelia Joya; Salvador Herrero; Juan Ferré; Patricia Hernández Martinez. 2021. "Hetero-oligomerization of Bacillus thuringiensis Cry1A proteins enhance binding to the ABCC2 transporter of Spodoptera exigua." Biochemical Journal , no. : 1.

Communication
Published: 20 May 2021 in Toxins
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Laboratory selection for resistance of field populations is a well-known and useful tool to understand the potential of insect populations to evolve resistance to insecticides. It provides us with estimates of the frequency of resistance alleles and allows us to study the mechanisms by which insects developed resistance to shed light on the mode of action and optimize resistance management strategies. Here, a field population of Mythimna separata was subjected to laboratory selection with either Vip3Aa, Cry1Ab, or Cry1F insecticidal proteins from Bacillus thuringiensis. The population rapidly evolved resistance to Vip3Aa reaching, after eight generations, a level of >3061-fold resistance, compared with the unselected insects. In contrast, the same population did not respond to selection with Cry1Ab or Cry1F. The Vip3Aa resistant population did not show cross resistance to either Cry1Ab or Cry1F. Radiolabeled Vip3Aa was tested for binding to brush border membrane vesicles from larvae from the susceptible and resistant insects. The results did not show any qualitative or quantitative difference between both insect samples. Our data, along with previous results obtained with other Vip3Aa-resistant populations from other insect species, suggest that altered binding to midgut membrane receptors is not the main mechanism of resistance to Vip3Aa.

ACS Style

Yudong Quan; Jing Yang; Yueqin Wang; Patricia Hernández-Martínez; Juan Ferré; Kanglai He. The Rapid Evolution of Resistance to Vip3Aa Insecticidal Protein in Mythimna separata (Walker) Is Not Related to Altered Binding to Midgut Receptors. Toxins 2021, 13, 364 .

AMA Style

Yudong Quan, Jing Yang, Yueqin Wang, Patricia Hernández-Martínez, Juan Ferré, Kanglai He. The Rapid Evolution of Resistance to Vip3Aa Insecticidal Protein in Mythimna separata (Walker) Is Not Related to Altered Binding to Midgut Receptors. Toxins. 2021; 13 (5):364.

Chicago/Turabian Style

Yudong Quan; Jing Yang; Yueqin Wang; Patricia Hernández-Martínez; Juan Ferré; Kanglai He. 2021. "The Rapid Evolution of Resistance to Vip3Aa Insecticidal Protein in Mythimna separata (Walker) Is Not Related to Altered Binding to Midgut Receptors." Toxins 13, no. 5: 364.

Review article
Published: 17 February 2021 in Microbiology and Molecular Biology Reviews
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Extensive use of chemical insecticides adversely affects both environment and human health. One of the most popular biological pest control alternatives are bioinsecticides based on Bacillus thuringiensis .

ACS Style

Daniel Pinos; Ascensión Andrés-Garrido; Juan Ferré; Patricia Hernández-Martínez. Response Mechanisms of Invertebrates to Bacillus thuringiensis and Its Pesticidal Proteins. Microbiology and Molecular Biology Reviews 2021, 85, 1 .

AMA Style

Daniel Pinos, Ascensión Andrés-Garrido, Juan Ferré, Patricia Hernández-Martínez. Response Mechanisms of Invertebrates to Bacillus thuringiensis and Its Pesticidal Proteins. Microbiology and Molecular Biology Reviews. 2021; 85 (1):1.

Chicago/Turabian Style

Daniel Pinos; Ascensión Andrés-Garrido; Juan Ferré; Patricia Hernández-Martínez. 2021. "Response Mechanisms of Invertebrates to Bacillus thuringiensis and Its Pesticidal Proteins." Microbiology and Molecular Biology Reviews 85, no. 1: 1.

Editorial
Published: 10 December 2020 in Toxins
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Bacillus thuringiensis (Bt)-based products are the most successful microbial insecticides to date

ACS Style

Yolanda Bel; Juan Ferré; Patricia Hernández-Martínez. Bacillus thuringiensis Toxins: Functional Characterization and Mechanism of Action. Toxins 2020, 12, 785 .

AMA Style

Yolanda Bel, Juan Ferré, Patricia Hernández-Martínez. Bacillus thuringiensis Toxins: Functional Characterization and Mechanism of Action. Toxins. 2020; 12 (12):785.

Chicago/Turabian Style

Yolanda Bel; Juan Ferré; Patricia Hernández-Martínez. 2020. "Bacillus thuringiensis Toxins: Functional Characterization and Mechanism of Action." Toxins 12, no. 12: 785.

Journal article
Published: 19 June 2020 in Toxins
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The Vip3Aa insecticidal protein from Bacillus thuringiensis (Bt) is produced by specific transgenic corn and cotton varieties for efficient control of target lepidopteran pests. The main threat to this technology is the evolution of resistance in targeted insect pests and understanding the mechanistic basis of resistance is crucial to deploy the most appropriate strategies for resistance management. In this work, we tested whether alteration of membrane receptors in the insect midgut might explain the >2000-fold Vip3Aa resistance phenotype in a laboratory-selected colony of Heliothis virescens (Vip-Sel). Binding of 125I-labeled Vip3Aa to brush border membrane vesicles (BBMV) from 3rd instar larvae from Vip-Sel was not significantly different from binding in the reference susceptible colony. Interestingly, BBMV from Vip-Sel larvae showed dramatically reduced levels of membrane-bound alkaline phosphatase (mALP) activity, which was further confirmed by a strong downregulation of the membrane-bound alkaline phosphatase 1 (HvmALP1) gene. However, the involvement of HvmALP1 as a receptor for the Vip3Aa protein was not supported by results from ligand blotting and viability assays with insect cells expressing HvmALP1.

ACS Style

Daniel Pinos; Maissa Chakroun; Anabel Millán-Leiva; Juan Luis Jurat-Fuentes; Denis J. Wright; Patricia Hernández-Martínez; Juan Ferré. Reduced Membrane-Bound Alkaline Phosphatase Does Not Affect Binding of Vip3Aa in a Heliothis virescens Resistant Colony. Toxins 2020, 12, 409 .

AMA Style

Daniel Pinos, Maissa Chakroun, Anabel Millán-Leiva, Juan Luis Jurat-Fuentes, Denis J. Wright, Patricia Hernández-Martínez, Juan Ferré. Reduced Membrane-Bound Alkaline Phosphatase Does Not Affect Binding of Vip3Aa in a Heliothis virescens Resistant Colony. Toxins. 2020; 12 (6):409.

Chicago/Turabian Style

Daniel Pinos; Maissa Chakroun; Anabel Millán-Leiva; Juan Luis Jurat-Fuentes; Denis J. Wright; Patricia Hernández-Martínez; Juan Ferré. 2020. "Reduced Membrane-Bound Alkaline Phosphatase Does Not Affect Binding of Vip3Aa in a Heliothis virescens Resistant Colony." Toxins 12, no. 6: 409.

Journal article
Published: 22 March 2019 in Toxins
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ABC proteins are primary-active transporters that require the binding and hydrolysis of ATP to transport substrates across the membrane. Since the first report of an ABCC2 transporter as receptor of Cry1A toxins, the number of ABC transporters known to be involved in the mode of action of Cry toxins has increased. In Spodoptera exigua, a mutation in the SeABCC2 gene is described as genetically linked to resistance to the Bt-product XentariTM. This mutation affects an intracellular domain involved in ATP binding, but not the extracellular loops. We analyzed whether this mutation affects the role of the SeABCC2 as a functional receptor to Cry1A toxins. The results show that Sf21 cells expressing the truncated form of the transporter were susceptible to Cry1A toxins. Moreover, specific Cry1Ac binding was observed in those cells expressing the truncated SeABCC2. Additionally, no differences in the irreversible Cry1Ac binding component (associated with the toxin insertion into the membrane) were observed when tested in Sf21 cells expressing either the full-length or the truncated form of the SeABCC2 transporter. Therefore, our results point out that the partial lack of the nucleotide binding domain II in the truncated transporter does not affect its functionality as a Cry1A receptor.

ACS Style

Daniel Pinos; María Martínez-Solís; Salvador Herrero; Juan Ferré; Patricia Hernández-Martínez. The Spodoptera exigua ABCC2 Acts as a Cry1A Receptor Independently of its Nucleotide Binding Domain II. Toxins 2019, 11, 172 .

AMA Style

Daniel Pinos, María Martínez-Solís, Salvador Herrero, Juan Ferré, Patricia Hernández-Martínez. The Spodoptera exigua ABCC2 Acts as a Cry1A Receptor Independently of its Nucleotide Binding Domain II. Toxins. 2019; 11 (3):172.

Chicago/Turabian Style

Daniel Pinos; María Martínez-Solís; Salvador Herrero; Juan Ferré; Patricia Hernández-Martínez. 2019. "The Spodoptera exigua ABCC2 Acts as a Cry1A Receptor Independently of its Nucleotide Binding Domain II." Toxins 11, no. 3: 172.

Journal article
Published: 02 August 2018 in Insect Biochemistry and Molecular Biology
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Cry proteins from Bacillus thuringiensis (Bt) have been used to control insect pests either as formulated sprays or as in Bt-crops. However, field-evolved resistance to Bt proteins is threatening the long-term use of Bt products. The SeABCC2 locus has been genetically linked to resistance to a Bt bioinsecticide (Xentari™) in Spodoptera exigua (a mutation producing a truncated form of the transporter lacking an ATP binding domain was found in the resistant insects). Here, we investigated the role of SeABCC2 in the mode of action of Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ca, and two Cry1A-1Ca hybrids by expressing the receptor in Sf21 and HEK293T cell lines. Cell toxicity assays showed that Sf21 cells expressing SeABCC2 become susceptible to Cry1A proteins. HEK293T cells expressing the transporter were found susceptible to Cry1A proteins but not to Cry1Ca. The results with the Cry1A-1Ca hybrids suggest that domain II from Cry1Ab/c is crucial for the toxicity to Sf21 cells, whereas domain III from Cry1Aa/b is crucial for the toxicity to HEK293T cells. Binding assays showed that the Cry1Ac binding is of high affinity and specific to cells expressing the SeABCC2 transporter. Heterologous competition experiments support a model in which domain II of Cry1Ab/c has a common binding site in the SeABCC2 protein, whereas domain III of Cry1Aa/b binds to a different binding site in the SeABCC2 protein.

ACS Style

María Martínez-Solís; Daniel Pinos; Haruka Endo; Leivi Portugal; Ryoichi Sato; Juan Ferré; Salvador Herrero; Patricia Hernández-Martínez. Role of Bacillus thuringiensis Cry1A toxins domains in the binding to the ABCC2 receptor from Spodoptera exigua. Insect Biochemistry and Molecular Biology 2018, 101, 47 -56.

AMA Style

María Martínez-Solís, Daniel Pinos, Haruka Endo, Leivi Portugal, Ryoichi Sato, Juan Ferré, Salvador Herrero, Patricia Hernández-Martínez. Role of Bacillus thuringiensis Cry1A toxins domains in the binding to the ABCC2 receptor from Spodoptera exigua. Insect Biochemistry and Molecular Biology. 2018; 101 ():47-56.

Chicago/Turabian Style

María Martínez-Solís; Daniel Pinos; Haruka Endo; Leivi Portugal; Ryoichi Sato; Juan Ferré; Salvador Herrero; Patricia Hernández-Martínez. 2018. "Role of Bacillus thuringiensis Cry1A toxins domains in the binding to the ABCC2 receptor from Spodoptera exigua." Insect Biochemistry and Molecular Biology 101, no. : 47-56.