Evolution of a subtilisin-like protease gene family in the grass endophytic fungus Epichloe festucae

Background: Subtilisin-like proteases ( SLPs) form a superfamily of enzymes that act to degrade protein substrates. In fungi, SLPs can play either a general nutritive role, or may play specific roles in cell metabolism, or as pathogenicity or virulence factors. Results: Fifteen different genes encoding SLPs were identified in the genome of the grass endophytic fungus Epichloe festucae. Phylogenetic analysis indicated that these SLPs belong to four different subtilisin families: proteinase K, kexin, pyrolysin and subtilisin. The pattern of intron loss and gain is consistent with this phylogeny. E. festucae is exceptional in that it contains two kexinlike genes. Phylogenetic analysis in Hypocreales fungi revealed an extensive history of gene loss and duplication. Conclusion: This study provides new insights into the evolution of the SLP superfamily in filamentous fungi.