Biology subjects

Shapaval, V.

Publications and source records attributed to Shapaval, V..

3 recordsLinked to original sources

bioRxiv2025

Mechanistic Insights into Keratin Degradation by Onygena corvina

Keratin-rich byproducts from the poultry, textile, and leather industries pose a significant challenge for sustainable waste management due to their highly recalcitrant nature. While microbial degradation may offer a viable solution, the mechanisms underlying keratin breakdown remain largely unexplored. In this study, we employed a high-resolution proteogenomic approach to characterize the keratinolytic machinery of Onygena corvina, a non-pathogenic saprophytic fungus. Using a membrane agar plate method with insoluble substrates, we obtained secretomes enriched in secreted and substrate-bound proteins during growth on - and {beta}-keratin-rich substrates, specifically wool and feather meal. Our findings reveal that O. corvina has a richer proteolytic machinery than previously reported, including enzymes that are used across keratin types, as well as enzymes that are specifically targeted to either - or {beta}-keratin. In addition to proteases, the secretomes contain numerous other proteins, including cell wall-modifying enzymes, oxidoreductases, esterases, phosphatases, and sialidases that are involved in the deconstruction of keratin. We propose that these additional enzymes destabilize keratin through a combination of mechanical keratinolysis, removal of post-translational modifications, reduction of disulfide bonds, and cleavage of isopeptide bonds, thereby enhancing proteolytic accessibility. Interestingly, keratin degradation by O. corvina was most efficient when using mixed substrates containing both feather and wool meal. These novel insights into the keratinolytic system of O. corvina underscore the importance of considering synergistic enzyme interactions when developing biotechnological approaches for valorization of keratin-rich by-products.

molecular biology↗

bioRxiv2025

Calcium starvation leads to strain-specific gene regulation of lipid and carotenoid production in Mucor Circinelloides

AO_SCPLOWBSTRACTC_SCPLOWFungi are pivotal in transitioning to a bio-based, circular economy due to their ability to transform organic material into valuable products such as organic acids, enzymes, and drugs. Mucor circinelloides is a model organism for studying lipogenesis and it particularly promising for its metabolic capabilities in producing oils like TAGs and carotenoids, influenced by environmental factors such as nutrient availability. Notably, strains VI04473 and FRR5020 have been identified for their potential in producing single-cell oils and carotenoids, respectively. Calcium starvation have previously been shown to have strain-specific effects, with VI04473 accumulating more lipids and FRR5020 producing more carotenoids. Here we used genome sequencing, comparative genomics, transcriptomics, and metabolite phenotyping to explore the genetic basis of lipid and carotenoid production under calcium starvation in these strains. We found extensive genomic rearrangements between these strains, as well as low conservation of gene regulatory responses to calcium depletion. This lack of conservation also applies to genes involved in lipid and carotenoid production, i.e. the lipidome. Several pathways show divergent regulation between strains, which explains the phenotypic divergence between VI04473 and FRR5020. The complex gene family evolution of several lipidome genes probably also affected specialization of these strains to calcium stress. Our study sheds light on the complexity of the evolution of metabolic networks in M. circinelloides. Understanding these genetic underpinnings can optimize the industrial use of M. circinelloides, enhancing lipid productivity and stress tolerance, and tailoring metabolic profiles for specific applications. This research advances our knowledge on complexity of fungal lipid metabolism and the role of calcium in regulating metabolic pathways.

genomics↗

bioRxiv2021

SmdA is a novel cell morphology determinant in Staphylococcus aureus

Cell division and cell wall synthesis in staphylococci need to be precisely coordinated and controlled to allow the cell to multiply while maintaining their nearly spherical shape. The mechanisms ensuring correct placement of the division plane and synthesis of new cell wall have been studied intensively, however, hitherto unknown factors and proteins are likely to play key roles in this complex interplay. We here identified and investigated a protein with major influence on cell morphology in Staphylococcus aureus. The protein, named SmdA (for staphylococcal morphology determinant A), is a membrane-protein with septum-enriched localization. By CRISPRi knockdown and overexpression combined with different microscopy techniques, we demonstrate that proper levels of SmdA is necessary for cell division, including septum formation and cell splitting. We also identified conserved residues in SmdA that are critical for its functionality. Pulldown- and bacterial two-hybrid interaction experiments showed that SmdA interacts with several known cell division- and cell wall synthesis proteins, including penicillin binding proteins (PBPs) and EzrA. Notably, SmdA also affects susceptibility to cell wall targeting antibiotics, particularly in methicillin-resistant S. aureus (MRSA). Together, our results show that S. aureus is dependent on balanced amounts of membrane-attached SmdA in order to carry out proper cell division. ImportanceStaphylococcus aureus is an important human and animal pathogen. Antibiotic resistance is a major problem in treatment of staphylococcal infections, and cell division and cell wall synthesis factors have previously been shown to modulate susceptibility to antibiotics in this species. In the current work we investigated the function of an essential protein named SmdA, which was identified based on its septal localization and knockdown phenotype resulting in defective cellular morphologies. We demonstrate that this protein is critical for normal cell division in S. aureus. Depletion of SmdA sensitize resistant staphylococci to {beta}-lactam antibiotics. This work thus reveals a new staphylococcal cell division factor and a potential future target for narrow spectrum antimicrobials or compounds to resensitize antibiotic resistant staphylococcal strains.

microbiology↗