Trypanosoma cruzi arginine kinase characterization and cloning. A novel energetic pathway in protozoan parasites

PEREIRA, CLAUDIO A.; ALONSO, GUILLERMO D.; PAVETO, M. CRISTINA; IRIBARREN, ADOLFO; CABANAS, M. LAURA; TORRES, HÉCTOR N.; FLAWIÁ, MIRTHA M.

JOURNAL OF BIOLOGICAL CHEMISTRY

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Año: 2000 vol. 275 p. 1495 - 1501

0021-9258

This work contains the first description of a guanidino kinase in a flagellar unicellular parasite. The enzyme phosphorylates L-arginine and was characterized in preparations from Trypanosoma cruzi, the ethiological agent of Chagas´ disease. The activity requires ATP and a divalent cation. Under Standard assay conditions (1 mM L-arginine), the presence of 5-fold higher concentrations of canavanine or histidine produced a greater than 50% enzyme inhibition. The base sequence of this enzyme revealed an open reading frame of 357 amino acids and a molecular weight of 40,201. The amino acid sequence shows all of the characteristic consensus blocks of the ATP:guanidino phosphotransferase family and a putative ´actinin-type´ actin-binding domain. The highest amino acid identities of the T. cruzi sequence, about 70%, were with arginine kinases from Arthropoda. Southern and chromosome blots revealed that the kinase is encoded by a single-copy gene. Moreover, Northern blot analysis showed an mRNA subpopulation of about 2.0 kilobases, and Western blotting of T. cruzi-soluble polypeptides revealed a 40-kDa band. The finding in the parasite of a phosphagen and its biosynthetic pathway, which are totally different from those in mammalian host tissues, points out this arginine kinase as a possible chemotherapy target for Chagas´ disease.