The Aspergillus fumigatus mepB gene encodes an 82 kDa intracellular metalloproteinase structurally related to mammalian thimet oligopeptidases

Abstract

Aspergillus fumigatus produces an 82 kDa intracellular metalloproteinase that hydrolyses the Pz-peptide, 4-phenylazobenzyloxycarbonyl-Pro-Leu-Gly-Pro-Arg, a typical substrate of members of the thimet oligopeptidase family which is ubiquitously distributed across animal species. The A. fumigatus mepB gene encoding this 82 kDa metalloproteinase was cloned and sequenced. Analysis of the deduced amino acid sequence of mepB showed that the MepB protein is a cytosolic zinc metalloproteinase of the thimet oligopeptidase family (M3) and as such is probably involved in the intracellular degradation of small peptides. An A. fumigatus mutant that lacks the MepB Pz-peptidolytic activity was constructed by gene disruption at the mepB locus. Analysis of this mutant did not reveal any detectable phenotype.