Ectophosphatase activity in conidial forms of Fonsecaea pedrosoi is modulated by exogenous phosphate and influences fungal adhesion to mammalian cells.
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 (P(i)). Accordingly, removal of P(i) 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 enzyme 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 P(i) (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.
Kneipp
Lucimar F
LF
Instituto de Microbiologia Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-590, Brazil.
Rodrigues
Marcio L
ML
Holandino
Carla
C
Esteves
Fabiano F
FF
Souto-Padrón
Thais
T
Alviano
Celuta S
CS
Travassos
Luiz R
LR
Meyer-Fernandes
José R
JR
D000818:Animals; D001203:Ascomycota / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D002448:Cell Adhesion / Q000187:drug effects* / Q000502:physiology; D002460:Cell Line; D003470:Culture Media; D004847:Epithelial Cells; D010710:Phosphates / Q000494:pharmacology*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*
D003470:Culture Media; D010710:Phosphates; D010744:Phosphoric Monoester Hydrolases