title: A 25-kDa serine peptidase with keratinolytic activity secreted by Coccidioides immitis.
abstract: Coccidioides immitis is the causative agent of coccidioidomycosis, a systemic mycosis that attacks humans and a wide variety of animals. In the present study, we showed that the C. immitis mycelial form is able to release proteolytic enzyme into the extracellular environment. Under chemically defined growth conditions, mycelia secreted seven distinct polypeptides ranging from 15 to 65 kDa and an extracellular peptidase of 25 kDa. This enzyme had its activity fully inhibited by phenylmethylsulphonyl fluoride, a serine peptidase inhibitor. Conversely, metallo, cysteine, and aspartyl peptidase inhibitors did not alter the 25-kDa enzyme behavior. This extracellular serine peptidase was able to degrade keratin, a fibrous protein that composes human epidermis. Additionally, this peptidase cleaved different protein substrates, including gelatin, casein, hemoglobin, and albumin. Curiously, an 18-kDa serine peptidase activity was evidenced solely when casein was used as the co-polymerized protein substrate into the gel. The existence of different secreted peptidases could be advantageous for the adaptation of C. immitis to distinct environments during its complex life cycle.
authors.affiliation: Departamento de Microbiologia Geral, Instituto de Microbiologia Prof. Paulo de Góes (IMPPG), Centro de Ciências da Saúde (CCS), Universidade Federal do Rio de Janeiro (UFRJ), Ilha do Fundão, Rio de Janeiro 21941-902, RJ, Brazil.
authors.forename: Bárbara Gabriela Brum
authors.initials: BG
authors.lastname: Lopes
authors.forename: André Luis Souza Dos
authors.initials: AL
authors.lastname: Santos
authors.forename: Cláudia de Carvalho Falci
authors.initials: Cde C
authors.lastname: Bezerra
authors.forename: Bodo
authors.initials: B
authors.lastname: Wanke
authors.forename: Márcia
authors.initials: M
authors.lastname: Dos Santos Lazéra
authors.forename: Marília Martins
authors.initials: MM
authors.lastname: Nishikawa
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Mazotto
authors.forename: Vânia Monteiro
authors.initials: VM
authors.lastname: Kussumi
authors.forename: Rosa Maria Tavares
authors.initials: RM
authors.lastname: Haido
authors.forename: Alane Beatriz
authors.initials: AB
authors.lastname: Vermelho
mesh_terms: D000818:Animals; D001938:Brazil; D003045:Coccidioides / Q000201:enzymology* / Q000302:isolation & purification / Q000472:pathogenicity; D003047:Coccidioidomycosis / Q000382:microbiology; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D010447:Peptide Hydrolases; C035855:keratinase; D012697:Serine Endopeptidases