Overexpression of a Zn2+-sensitive soluble exopolyphosphatase from Trypanosoma cruzi depletes polyphosphate and affects osmoregulation

J Biol Chem. 2007 Nov 2;282(44):32501-10. doi: 10.1074/jbc.M704841200. Epub 2007 Sep 7.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acid Anhydride Hydrolases / chemistry
  • Acid Anhydride Hydrolases / genetics
  • Acid Anhydride Hydrolases / metabolism*
  • Amino Acid Sequence
  • Animals
  • Cloning, Molecular
  • Molecular Sequence Data
  • Polyphosphates / metabolism*
  • Protein Structure, Tertiary
  • Protozoan Proteins / chemistry
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Sequence Homology
  • Trypanosoma cruzi / enzymology*
  • Water-Electrolyte Balance*
  • Zinc / metabolism*


  • Polyphosphates
  • Protozoan Proteins
  • Recombinant Proteins
  • Acid Anhydride Hydrolases
  • exopolyphosphatase
  • Zinc

Associated data

  • GENBANK/AF545106
  • GENBANK/AY178275