Secreted Metalloprotease Gene Family of Microsporum canis

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Abstract
Keratinolytic proteases secreted by dermatophytes are likely to be virulence-related factors. Microsporum canis , the main agent of dermatophytosis in dogs and cats, causes a zoonosis that is frequently reported. Using Aspergillus fumigatus metalloprotease genomic sequence ( MEP ) as a probe, three genes ( MEP1 , MEP2 , and MEP3 ) were isolated from an M. canis genomic library. They presented a quite-high percentage of identity with both A. fumigatus MEP and Aspergillus oryzae neutral protease I genes. At the amino acid level, they all contained an HEXXH consensus sequence, confirming that these M. canis genes ( MEP genes) encode a zinc-containing metalloprotease gene family. Furthermore, MEP3 was found to be the gene encoding a previously isolated M. canis 43.5-kDa keratinolytic metalloprotease, and was successfully expressed as an active recombinant enzyme in Pichia pastoris . Reverse transcriptase nested PCR performed on total RNA extracted from the hair of M. canis -infected guinea pigs showed that at least MEP2 and MEP3 are produced during the infection process. This is the first report describing the isolation of a gene family encoding potential virulence-related factors in dermatophytes.