Biochemical and genetic analysis of Ecm14, a conserved fungal pseudopeptidase

Experimental evolution and hybridization enhance the fermentative capacity of wild Saccharomyces eubayanus strains

Lager beer is traditionally fermented using Saccharomyces pastorianus. However, the limited availability of lager yeast strains restricts the potential range of beer profiles. Recently, Saccharomyces eubayanus strains showed the potential to impart novel aromas to beer, with slower fermentation rates than commercial strains. Here, we applied experimental evolution to nine S. eubayanus strains using three different selective conditions to generate improved strains to fermentative environments. We observed environment-dependent fitness changes across strains, with ethanol-enriched media resulting in the greatest fitness improvement. We identified subtelomeric genomic changes in a deficient fermentative strain underlying the greatest fitness improvement. Gene expression analysis and genome sequencing identified genes associated with oxidative stress, amino acid metabolism, sterol biosynthesis, and vacuole morphology underlying differences between evolved and the ancestral strain, revealing the cellular processes underlying fermentation improvement. A hybridization strategy between two evolved strains allowed us to expand the phenotypic space of the F2 segregants, obtaining strains with a 13.7% greater fermentative capacity relative to the best evolved parental strains. Our study highlights the potential of integrating experimental evolution and hybridization to enhance the fermentation capacity of wild yeast strains, offering strengthened solutions for industrial applications and highlighting the potential of Patagonian S. eubayanus in brewing.

Inactive metallopeptidase homologs: the secret lives of pseudopeptidases

Inactive enzyme homologs, or pseudoenzymes, are proteins, found within most enzyme families, that are incapable of performing catalysis. Rather than catalysis, they are involved in protein-protein interactions, sometimes regulating the activity of their active enzyme cousins, or scaffolding protein complexes. Pseudoenzymes found within metallopeptidase families likewise perform these functions. Pseudoenzymes within the M14 carboxypeptidase family interact with collagens within the extracellular space, while pseudopeptidase members of the M12 "a disintegrin and metalloprotease" (ADAM) family either discard their pseudopeptidase domains as unnecessary for their roles in sperm maturation or utilize surface loops to enable assembly of key complexes at neuronal synapses. Other metallopeptidase families contain pseudopeptidases involved in protein synthesis at the ribosome and protein import into organelles, sometimes using their pseudo-active sites for these interactions. Although the functions of these pseudopeptidases have been challenging to study, ongoing work is teasing out the secret lives of these proteins.

First Insight into the Degradome of Aspergillus ochraceus: Novel Secreted Peptidases and Their Inhibitors

Aspergillus fungi constitute a pivotal element within ecosystems, serving as both contributors of biologically active compounds and harboring the potential to cause various diseases across living organisms. The organism's proteolytic enzyme complex, termed the degradome, acts as an intermediary in its dynamic interaction with the surrounding environment. Using techniques such as genome and transcriptome sequencing, alongside protein prediction methodologies, we identified putative extracellular peptidases within Aspergillus ochraceus VKM-F4104D. Following manual annotation procedures, a total of 11 aspartic, 2 cysteine, 2 glutamic, 21 serine, 1 threonine, and 21 metallopeptidases were attributed to the extracellular degradome of A. ochraceus VKM-F4104D. Among them are enzymes with promising applications in biotechnology, potential targets and agents for antifungal therapy, and microbial antagonism factors. Thus, additional functionalities of the extracellular degradome, extending beyond mere protein substrate digestion for nutritional purposes, were demonstrated.