Immobilization of the recombinant, plant-derived Petroselinum crispum phenylalanine ammonia lyase (PcPAL) in electrospun matrices have the potential to create promising, easy-to-use biocatalysts. Polylactic acid (PLA) a biologically inert, commercial biopolymer, was chosen as the material of the carrier system. PLA could be electrospun properly only from water-immiscible organic solvents, which limits its application as a carrier of sensitive biological objects. The emulsion electrospinning is a proper solution to overcome this issue using non-ionic emulsifiers with different hydrophilic-lipophilic balance (HLB) values. The stabilized emulsion could protect the sensitive PcPAL dissolved in the aqueous buffer phase and improve fiber formation, plus help to keep the biocatalytic activity of enzymes. In this study, the first approach is described to produce PLA nanofibers containing PcPAL enzymes by emulsion electrospinning and to use the resulted biocatalyst in the ammonia elimination reaction from l-phenylalanine.

In human cells two dUTPase isoforms have been described: one nuclear (DUT-N) and one mitochondrial (DUT-M), with cognate localization signals. In contrast, here we identified two additional isoforms; DUT-3 without any localization signal and DUT-4 with the same nuclear localization signal as DUT-N. Based on an RT-qPCR method for simultaneous isoform-specific quantification we analysed the relative expression patterns in 20 human cell lines of highly different origins. We found that the DUT-N isoform is expressed by far at the highest level, followed by the DUT-M and the DUT-3 isoform. A strong correlation between expression levels of DUT-M and DUT-3 suggests that these two isoforms may share the same promoter. We analysed the effect of serum starvation on the expression of dUTPase isoforms compared to non-treated cells and found that the mRNA levels of DUT-N decreased in A-549 and MDA-MB-231 cells, but not in HeLa cells. Surprisingly, upon serum starvation DUT-M and DUT-3 showed a significant increase in the expression, while the expression level of the DUT-4 isoform did not show any changes. Taken together our results indicate that the cellular dUTPase supply may also be provided in the cytoplasm and starvation stress induced expression changes are cell line dependent.

Deoxyuridine in DNA has recently been in the focus of research due to its intriguing roles in several physiological and pathophysiological situations. Although not an orthodox DNA base, uracil may appear in DNA via either cytosine deamination or thymine-replacing incorporations. Since these alterations may induce mutation or may perturb DNA–protein interactions, free living organisms from bacteria to human contain several pathways to counteract uracilation. These efficient and highly specific repair routes uracil-directed excision repair initiated by representative of uracil-DNA glycosylase families. Interestingly, some bacteriophages exist with thymine-lacking uracil-DNA genome. A detailed understanding of the strategy by which such phages can replicate in bacteria where an efficient repair pathway functions for uracil-excision from DNA is expected to reveal novel inhibitors that can also be used for biotechnological applications. Here, we also review the several potential biotechnological applications already implemented based on inhibitors of uracil-excision repair, such as Crispr-base-editing and detection of nascent uracil distribution pattern in complex genomes.