Multiplication of an ancestral gene encoding secreted fungalysin preceded species differentiation in the dermatophytes Trichophyton and Microsporum.
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.
Jousson
Olivier
O
Dermatology Service (DHURDV), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
Léchenne
Barbara
B
Dermatology Service (DHURDV), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
Bontems
Olympia
O
Dermatology Service (DHURDV), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
Capoccia
Sabrina
S
Dermatology Service (DHURDV), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
Mignon
Bernard
B
Department of Infectious and Parasitic Diseases, Faculty of Veterinary Medicine, University of Liège, Belgium.
Barblan
Jachen
J
Protein Analysis Facility, Institute of Biochemistry, University of Lausanne, Epalinges, Switzerland.
Quadroni
Manfredo
M
Protein Analysis Facility, Institute of Biochemistry, University of Lausanne, Epalinges, Switzerland.
Monod
Michel
M
Dermatology Service (DHURDV), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
D001230:Aspergillus / Q000201:enzymology / Q000235:genetics; D001483:Base Sequence; D017931:DNA Primers; D003881:Dermatomycoses / Q000382:microbiology; D005656:Fungal Proteins / Q000235:genetics; D006801:Humans; D016013:Likelihood Functions; D013058:Mass Spectrometry; D045726:Metalloproteases / Q000235:genetics*; D008864:Microsporum / Q000145:classification / Q000235:genetics* / Q000254:growth & development; D010802:Phylogeny; D014005:Tinea / Q000382:microbiology; D014249:Trichophyton / Q000145:classification / Q000235:genetics* / Q000254:growth & development
D017931:DNA Primers; D005656:Fungal Proteins; D045726:Metalloproteases