Fungal lifestyle reflected in serine protease repertoire

Marta M Stepniewska-Dziubinska,Kamil Steczkiewicz,Julia Pawlowska,Agata Dziedzic,Krzysztof Ginalski,Anna Muszewska

doi:10.1038/s41598-017-09644-w

Marta M Stepniewska-Dziubinska, Kamil Steczkiewicz + Show 4 more

Open Access

https://doi.org/10.1038/s41598-017-09644-w

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Abstract

Fungi are able to switch between different lifestyles in order to adapt to environmental changes. Their ecological strategy is connected to their secretome as fungi obtain nutrients by secreting hydrolytic enzymes to their surrounding and acquiring the digested molecules. We focus on fungal serine proteases (SPs), the phylogenetic distribution of which is barely described so far. In order to collect a complete set of fungal proteases, we searched over 600 fungal proteomes. Obtained results suggest that serine proteases are more ubiquitous than expected. From 54 SP families described in MEROPS Peptidase Database, 21 are present in fungi. Interestingly, 14 of them are also present in Metazoa and Viridiplantae – this suggests that, except one (S64), all fungal SP families evolved before plants and fungi diverged. Most representatives of sequenced eukaryotic lineages encode a set of 13–16 SP families. The number of SPs from each family varies among the analysed taxa. The most abundant are S8 proteases. In order to verify hypotheses linking lifestyle and expansions of particular SP, we performed statistical analyses and revealed previously undescribed associations. Here, we present a comprehensive evolutionary history of fungal SP families in the context of fungal ecology and fungal tree of life.

Highlights

Serine proteases (SPs) are essential hydrolytic enzymes that utilize the catalytic serine residue for cleaving peptide bonds in proteins[1]
Fungi like other Eukaryotes possess an extensive set of housekeeping, intracellular serine proteases (SPs) involved in protein turnover, protein maturation, signal transduction and signal peptide cleavage to mention only a few, as well as a range of secreted SPs
Most studies of fungal SPs were focused on animal fungal pathogens and confirmed the extracellular proteolytic activity performed by SPs in Aspergillus fumigatus13,Candida albicans[14], Cryptococcus meningitis[15], Histoplasma capsulatum[16] and Paracoccidioides brasiliensis[13, 17]

Summary

Introduction

Serine proteases (SPs) are essential hydrolytic enzymes that utilize the catalytic serine residue for cleaving peptide bonds in proteins[1] They can be found in all living organisms and perform a variety of functions ranging from housekeeping: e.g. protein maturation, signal peptide cleavage, signal transduction, intracellular protein turnover, immune response, apoptosis, reproduction[2] and cytochrome processing in mitochondria, to nutrient breakdown and acquisition. Fungal intracellular SPs have been characterized mostly in Saccharomyces cerevisiae (for example, the mitochondrial Lon ATPase dependent protease PIM1 from S16 family23) and rarely in other non-model taxa In consequence, their detailed function often remains either extrapolated from very distant organisms (e.g. E_coli SppA protease from S49 family degrades signal peptides in the membrane24) or understudied (lysosomal Pro-Xaa carboxypeptidase, S28; X-Pro dipeptidyl-peptidase, S15). The aforementioned studies were limited by available genomic resources which are significantly enriched in sequences from taxa representing diverse lifestyles, and less biased towards pathogenic fungi

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