Identification and functional analysis of non-canonical Pepsin-like Aspartic Peptidases from fungi

REVUELTA MV; ARJEN TEN HAVE

Cordoba

Congreso; 2nd Congress of the Asocación Argentina de Bioinformática y Biología Computacional.; 2011

BackgroundRecent genome sequence projects have identified a stunning amount of Aspartic Proteases (APs) in ascomycete fungi. In our recent publicationwe show that most ascomycetes have more than 10 APs of which some have unprecedented characteristics. More recently we determined, based on a phylogeny of over 500 mostly fungal APs, that there are at least four AP-subfamilies, rather than the generally accepted two families of pepsin-like archetype and nepenthesin-like archetype APs. Both two new subfamilies, to which we refer to as Yapsins and Fungalapsins were composed of fungal APs only. However, since the phylogeny might have been biased by the presence of mostly fungal APs a new improved phylogeny including non-fungal AP datasets should be performed in order to corroborate the four clade phylogeny. Secondly, we wondered in which aspects these fungal APs differ from pepsin-like and nepensthesin-like APs.ResultsData mining was performed on 50 complete fungal genomes and nine complete genomes from non-fungal model organisms. The obtained phylogeny corroborates the existence of at least 4 subfamilies. The critical differences between the four subfamilies were then analysed using DIVERGE and HMMer Profile analysis. This allowed us to identify the key residues responsible for branch formation. It appears that the loop regions are fundamental for the AP diversification. A significant amount of biochemical research previously performed on the Yapsins has suggested these enzymes have a narrow substrate specificity. Comparative 3D analysis shows the basis of this substrate specificity is determined by two acidic residues on a surface loop that moves towards the active site upon autocatalytic activation of the zymogen.ConclusionsEukaryotic APs form interesting subjects for structure-function prediction since they show high sequence variability. The phylogeny indicates specialization of sequences. The four subfamilies found show clear differences among each other, which allows us to speculate regarding their function.