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Characterization of an ecto-ATPase activity in Cryptococcus neoformans
Itallo Collopy Junior1, Marcio L Rodrigues, Celuta S Alviano
1Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, CCS, Bloco H, Cidade Universitária, Ilha do Fundão, 21541-590 Rio de Janeiro, RJ, Brazil.
FEMS Yeast Research
|June 14, 2005
Summary
A surface enzyme, ecto-adenosine-triphosphatase (ATPase), was found in Cryptococcus neoformans. This enzyme affects fungal physiology and may influence susceptibility to antifungal drugs like fluconazole.
Area of Science:
- Mycology
- Biochemistry
- Molecular Biology
Background:
- Cryptococcus neoformans causes serious infections, particularly in immunocompromised individuals.
- Understanding fungal cell surface mechanisms is crucial for developing targeted therapies.
Purpose of the Study:
- To identify and characterize a surface ATPase in Cryptococcus neoformans.
- To investigate the enzyme's activity, substrate specificity, and potential role in fungal physiology and antifungal drug efficacy.
Main Methods:
- Enzyme assays using intact C. neoformans yeast cells to measure adenosine-triphosphate (ATP) hydrolysis.
- Kinetic analysis to determine kinetic parameters (Km) and substrate preferences.
- Testing the effects of various inhibitors and extracellular compounds on enzyme activity.
- Evaluating the impact of ATP presence on fluconazole susceptibility.
Main Results:
- A functional ecto-ATPase was identified on the surface of C. neoformans.
- The enzyme exhibited significant Mg(2+)-dependent ATP hydrolysis activity with a specific kinetic profile.
- The ecto-ATPase showed broad substrate specificity, hydrolyzing various nucleotide triphosphates.
- Presence of ATP reduced the susceptibility of C. neoformans to fluconazole.
Conclusions:
- Cryptococcus neoformans possesses an active ecto-ATPase on its cell surface.
- This enzyme likely plays a role in fungal physiology and may modulate the effectiveness of antifungal treatments.
- Further research into this ecto-ATPase could reveal new therapeutic targets.