1. Overexpression of a Zn2+-sensitive soluble exopolyphosphatase from Trypanosoma cruzi depletes polyphosphate and affects osmoregulation.
- Author
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Fang J, Ruiz FA, Docampo M, Luo S, Rodrigues JC, Motta LS, Rohloff P, and Docampo R
- Subjects
- Acid Anhydride Hydrolases chemistry, Acid Anhydride Hydrolases genetics, Amino Acid Sequence, Animals, Cloning, Molecular, Molecular Sequence Data, Protein Structure, Tertiary, Protozoan Proteins chemistry, Protozoan Proteins genetics, Recombinant Proteins chemistry, Recombinant Proteins genetics, Recombinant Proteins metabolism, Sequence Homology, Acid Anhydride Hydrolases metabolism, Polyphosphates metabolism, Protozoan Proteins metabolism, Trypanosoma cruzi enzymology, Water-Electrolyte Balance, Zinc metabolism
- Abstract
We report the cloning, expression, purification, and characterization of the Trypanosoma cruzi exopolyphosphatase (TcPPX). The product of this gene (TcPPX), has 383 amino acids and a molecular mass of 43.1 kDa. TcPPX differs from most exopolyphosphatases in its preference for short-chain polyphosphate (poly P). Heterologous expression of TcPPX in Escherichia coli produced a functional enzyme that had a neutral optimum pH and was dramatically inhibited by low concentrations of Zn2+, high concentrations of basic amino acids (lysine and arginine), and heparin. TcPPX is a processive enzyme and does not hydrolyze ATP, pyrophosphate, or p-nitrophenyl phosphate, although it hydrolyzes guanosine 5'-tetraphosphate very efficiently. Overexpression of TcPPX resulted in a dramatic decrease in total short-chain poly P and partial decrease in long-chain poly P. This was accompanied by a delayed regulatory volume decrease after hyposmotic stress. These results support the role of poly P in T. cruzi osmoregulation.
- Published
- 2007
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