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Microbiology 150 (2004), 3355-3362; DOI  10.1099/mic.0.27405-0
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Microbiology 150 (2004), 3355-3362; DOI  10.1099/mic.0.27405-0
© 2004 Society for General Microbiology

Ectophosphatase activity in conidial forms of Fonsecaea pedrosoi is modulated by exogenous phosphate and influences fungal adhesion to mammalian cells

Lucimar F. Kneipp1,4, Marcio L. Rodrigues1, Carla Holandino2, Fabiano F. Esteves3, Thais Souto-Padrón1, Celuta S. Alviano1, Luiz R. Travassos4 and José R. Meyer-Fernandes3

1 Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-590, Brazil
2 Departamento de Medicamentos, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-590, Brazil
3 Departamento de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-590, Brazil
4 Disciplina de Biologia Celular, Universidade Federal de São Paulo, São Paulo, SP 04023-062, Brazil

Correspondence
José R. Meyer-Fernandes
meyer{at}bioqmed.ufrj.br

A cell-wall-associated phosphatase in hyphae of Fonsecaea pedrosoi, a fungal pathogen causing chromoblastomycosis, was previously characterized by the authors. In the present work, the expression of an acidic ectophosphatase activity in F. pedrosoi conidial forms was investigated. The surface phosphatase activity in F. pedrosoi is associated with the cell wall, as demonstrated by transmission electron microscopy. This enzyme activity was strongly inhibited by exogenous inorganic phosphate (Pi). Accordingly, removal of Pi from the culture medium of F. pedrosoi resulted in a marked (130-fold) increase of ectophosphatase activity. With the artificial phosphatase substrate p-nitrophenyl phosphate, a Km value of 0·63±0·04 mM was estimated for the phosphatase activity of fungal cells strongly expressing the enyzme activity. This enzyme activity was not modulated by cations. Conidia with greater ectophosphatase activity showed greater adherence to mammalian cells than did fungi cultivated in the presence of Pi (low phosphatase activity). Surface phosphatase activity was apparently involved in the adhesion to host cells, since the enhanced attachment of F. pedrosoi to host cells was reversed by pre-treatment of conidia with phosphatase inhibitor. Since conidial forms are the putative infectious propagules in chromoblastomycosis, the expression and activity of acidic surface phosphatases in these cells may contribute to the early mechanisms required for disease establishment.

Abbreviations: CBM, chromoblastomycosis; FBS, fetal bovine serum; p-NP, p-nitrophenol; p-NPP, p-nitrophenyl phosphate






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