Abstract
Rhinocladiella aquaspersa is an etiologic agent of chromoblastomycosis, a subcutaneous chronic infectious disease. In the present work, we found that the three morphological forms of this fungus (conidia, mycelia and sclerotic bodies) expressed different levels of ecto-phosphatase activity. Our results demonstrated that surface conidial enzyme is an acid phosphatase, inhibited by sodium salts of molybdate, orthovanadate and fluoride and that the inhibition caused by orthovanadate and molybdate was irreversible. The conidial ecto-phosphatase efficiently released phosphate groups from different phosphorylated substrates, causing a higher rate of phosphate removal when p-nitrophenylphosphate was used as substrate. This ecto-enzyme of R. aquaspersa is modulated by Co2 + ions and inorganic phosphate (Pi). Accordingly, removal of Pi from the culture medium resulted in a marked (121-fold) increase of ecto-phosphatase activity. Surface phosphatase activity is apparently involved in fungal adhesive properties, since the attachment of R. aquaspersa to epithelial cells was reversed by the pre-treatment of the conidia with orthovanadate, molybdate and anti-phosphatase antibody. Corroborating this finding, conidia with greater ecto-phosphatase activity (grown in Pi-depleted medium) showed higher adherence to epithelial cells than fungi cultivated in the presence of Pi.
Acknowledgements
This work was supported by grants from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) and FIOCRUZ (Fundação Oswaldo Cruz).
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
This paper was first published online on Early Online on 9 February 2012.