Structure-Function Analysis of Sedolisins: Evolution of TriPeptidyl Peptidase and Endopeptidase Subfamilies in Fungi

ORTS, F; ARJEN TEN HAVE

BMC BIOINFORMATICS

BIOMED CENTRAL LTD

Lugar: Londres; Año: 2018 vol. 19

1471-2105

Background Sedolisins areacid proteases that are related to the basic subtilisins. They havebeen identified in all three superkingdoms but are not ubiquitous,although fungi that secrete acids as part of their lifestyle can haveup to six paralogs. Both TriPeptidylPeptidase (TPP) and endopeptidaseactivity have been identified and it has been suggested that thesecorrespond to separate subfamilies.ResultsWe studied eukaryoticsedolisins by computational analysis. A maximum likelihood tree showsone major clade containing non-fungal sequences only and two major aswell as two minor clades containing only fungal sequences. One of themajor fungal clade contains all known TPPs whereas the other containscharacterized endosedolisins. We identified four Cluster Specificinserts (CSIs) in endosedolisins, of which CSIs 1, 3 and 4 appear assolvent exposed according to structure modeling. Part of CSI2 isexposed but a short stretch forms a novel and partially buriedα-helixthat induces aconformational change near the binding pocket. We also identified atotal of 15 specificity determining positions (SDPs) of which five,identified in two independent analyses, form highly connected SDPsub-networks. Modeling of virtual mutants suggests a key role for theW307A or F307A substitution. The remaining four key SDPs physicallyinteract at the interface of the catalytic domain and the enzyme´sprosegment. Modeling of virtual mutants suggests these SDPs areindeed required to compensate the conformational change induced byCSI2 and the A307. One of the two small fungal clades concerns asubfamily that contains 213 sequences, is mostly similar to the majorTPP subfamily but differs, interestingly, in position 307, showingmostly isoleucine and threonine.Conclusions Analysisconfirms there are at least two sedolisin subfamilies in fungi: TPPsand endopeptidasesand suggests a third subfamily with unknown characteristics. Sequenceand functional diversification was centered around buried SDP307 andresulted in a conformational change of the pocket. Mutual Informationnetwork analysis forms a useful instrument in the corroboration ofpredicted SDPs.p { margin-bottom: 0.08in; direction: ltr; color: rgb(0, 0, 0); line-height: 200%; text-align: justify; }p.western { font-family: "Times New Roman", serif; font-size: 12pt; }p.cjk { font-family: "SimSun"; font-size: 12pt; }p.ctl { font-family: "Mangal"; font-size: 12pt; }a:link { }