Characterization of an ecto-ATPase activity in Cryptococcus neoformans

Nenhuma Miniatura disponível
Data
2005-07-01
Autores
Junior, I. C.
Rodrigues, M. L.
Alviano, C. S.
Travassos, Luiz Rodolpho [UNIFESP]
Meyer-Fernandes, JR
Orientadores
Tipo
Artigo
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Cryptococcus neoformans is the causative agent of pulmonary cryptococcosis and cryptococcal meningoencephalitis, which are major clinical manifestations in immunosuppressed patients. in the present study, a surface ATPase (ecto-ATPase) was identified in C. neoformans yeast cells. Intact yeasts hydrolyzed adenosine-5'-triphosphate (ATP) at a rate of 29.36 +/- 3.36 nmol Pi/h x 10(8) cells. in the presence of 5 mM MgCl2, this activity was enhanced around 70 times, and an apparent K-m for Mg-ATP corresponding to 0.61 mM was determined. Inhibitors of phosphatases, mitochondrial Mg2+-ATPases, V-ATPases, Na+-ATPases or P-ATPases had no effect on the cryptococcal ATPase, but extracellular impermeant compounds reduced enzyme activity in living cells. ATP was the best substrate for the cryptococcal ecto-enzyme, but it also efficiently hydrolyzed inosine 5'-triphosphate (ITP), cytidine 5'-triphosphate (CTP), guanosine 5'-triphosphate (GTP) and uridine-5'-triphosphate (UTP). in the presence of ATP, C. neoformans became less susceptible to the antifungal action of fluconazole. Our results are indicative of the occurrence of a C. neoformans ectoATPase that may have a role in fungal physiology. (c) 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
Descrição
Citação
Fems Yeast Research. Amsterdam: Elsevier B.V., v. 5, n. 10, p. 899-907, 2005.
Coleções