Jousson Olivier, Léchenne Barbara, Bontems Olympia, Capoccia Sabrina, Mignon Bernard, Barblan Jachen, Quadroni Manfredo, Monod Michel
Dermatology Service (DHURDV), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
Department of Infectious and Parasitic Diseases, Faculty of Veterinary Medicine, University of Liège, Belgium.
Microbiology (Reading). 2004 Feb;150(Pt 2):301-310. doi: 10.1099/mic.0.26690-0.
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.
皮肤癣菌是引起皮肤感染的人类和动物致病真菌，仅在角质层、指甲和毛发中生长。在以大豆蛋白作为唯一氮源的培养基中，红色毛癣菌、须癣毛癣菌和犬小孢子菌分泌了大量的蛋白水解活性。这种蛋白水解活性被邻菲啰啉抑制了55 - 75%，证明这三种菌都分泌了金属蛋白酶。利用基于烟曲霉、米曲霉和犬小孢子菌中先前鉴定的编码M36真菌溶素家族金属蛋白酶（MEP）的基因构建的共有探针，从红色毛癣菌、须癣毛癣菌和犬小孢子菌的基因组文库中分离出了一个由五个成员组成的MEP家族。对基因组和蛋白质序列的系统发育分析揭示了一个由五个主要分支组成的可靠树，每个分支都包括来自每个皮肤癣菌物种的一个MEP序列类型。每种MEP类型在不同物种间都具有显著的保守性（氨基酸序列同一性为72 - 97%）。树形拓扑结构清楚地表明，皮肤癣菌中MEP基因的倍增发生在物种分化之前。在以大豆蛋白作为唯一氮源的培养基中，分泌的Meps占总分泌蛋白提取物的19 - 36%；通过蛋白水解和质谱对蛋白条带进行表征，发现这三种皮肤癣菌物种分泌了由直系同源基因编码的两种Meps（Mep3和Mep4）。
