PARTIAL SEQUENCE-ANALYSIS OF A PLASMODIUM-VIVAX CATION TRANSPORTING ATPASE GENE HOMOLOG AND A PUTATIVE PSEUDOHOMOLOGUE

Molecular characterization of P. vivax is essential to develop suitabl e antimalarial drugs and vaccines. We describe here isolation and sequ ence analysis of a partial cDNA of a calcium ATPase as well as a putat ive pseudogene from this parasite. The immunoscreening of lambda gtll- P. vivax DNA library with patients serum has earlier resulted in the i solation of several seroreactive clones including Pv14. This clone con tains a 299 bp insert having 18 amino acids (aa) reading frame fused w ith beta galactosidase. A larger fragment of similar to 15 kb was isol ated from the EMBL3 library for Pv14 but it had only 2 extra aa in its reading frame. The far upstream region of Pv14 revealed a 101aa long putative open reading frame (ORF) showing homology to a variety of cal cium ATPases in the M8 and M9 transmembrane region; But in the absence of a transcript in the parasite could indicate that it represents a p seudogene. However, the real gene for calcium ATPase in P. vivax was d etected by RT-PCR using degenerate primers, designed from the conserve d sequences of energy transduction and phosphorylation domains. The am plified cDNA-PCR product of 550 bp was cloned and sequenced which show ed a significant aa homology to the calcium ATPase4 of P. falciparum. The present study, therefore, establishes the existence of calcium ion pumps in P. vivax which will be useful in drug development.