Multiplication of an ancestral gene encoding secreted fungalysin preceded species differentiation in the dermatophytes Trichophyton and Microsporum

Microbiology. 2004 Feb;150(Pt 2):301-310. doi: 10.1099/mic.0.26690-0.

Abstract

Dermatophytes are human and animal pathogenic fungi which cause cutaneous infections and grow exclusively in the stratum corneum, nails and hair. In a culture medium containing soy proteins as sole nitrogen source a substantial proteolytic activity was secreted by Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis. This proteolytic activity was 55-75 % inhibited by o-phenanthroline, attesting that metalloproteases were secreted by all three species. Using a consensus probe constructed on previously characterized genes encoding metalloproteases (MEP) of the M36 fungalysin family in Aspergillus fumigatus, Aspergillus oryzae and M. canis, a five-member MEP family was isolated from genomic libraries of T. rubrum, T. mentagrophytes and M. canis. A phylogenetic analysis of genomic and protein sequences revealed a robust tree consisting of five main clades, each of them including a MEP sequence type from each dermatophyte species. Each MEP type was remarkably conserved across species (72-97 % amino acid sequence identity). The tree topology clearly indicated that the multiplication of MEP genes in dermatophytes occurred prior to species divergence. In culture medium containing soy proteins as a sole nitrogen source secreted Meps accounted for 19-36 % of total secreted protein extracts; characterization of protein bands by proteolysis and mass spectrometry revealed that the three dermatophyte species secreted two Meps (Mep3 and Mep4) encoded by orthologous genes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aspergillus / enzymology
  • Aspergillus / genetics
  • Base Sequence
  • DNA Primers
  • Dermatomycoses / microbiology
  • Fungal Proteins / genetics
  • Humans
  • Likelihood Functions
  • Mass Spectrometry
  • Metalloproteases / genetics*
  • Microsporum / classification
  • Microsporum / genetics*
  • Microsporum / growth & development
  • Phylogeny
  • Tinea / microbiology
  • Trichophyton / classification
  • Trichophyton / genetics*
  • Trichophyton / growth & development

Substances

  • DNA Primers
  • Fungal Proteins
  • Metalloproteases