Trichomonas vaginalis: characterization of a family of P-type ATPase genes

Abstract

P-type ATPases are ion-transporting pumps that enable organisms to control cellular functions and survive changing environmental conditions by regulating internal ion concentrations. Eight P-type ATPases were identified in the amitochondriate protist Trichomonas vaginalis using polymerase chain reaction (PCR) amplification with oligonucleotide primers that recognize conserved motifs present in all P-type ATPases, the ATP phosphorylation site (DKTGTLT) and the ATP binding site (TGDGVND). Phylogenetic analysis and the presence of conserved motifs in predicted peptide sequences identify the Trichomonas ATPases as a sarcoplasmic-endoplasmic reticulum calcium pump (TVCA1); three additional Ca 2+ transporting pumps (TVCA2-4), three phospholipid translocases (TVAPLT1-3), and one P-type ATPase of unknown transport specificity (TVPATP8). Southern blot analyses indicate that the P-type ATPase genes are not linked and are present in single copy, except TVCA2 and TVCA4 which contain additional copies or closely related homologues within the genome. Transcripts of 3.1 kb for TVCA1, 3.0 kb for TVCA2, 2.9 kb for TVCA3, 4.0 kb for TVAPLT1, 4.2 kb for TVAPLT2, 3.9 kb for TVAPLT3, and 3.1 kb for TVPATP8 were detected by Northern blot analysis. No TVCA4 transcript was observed, however, RT-PCR amplification of a transcript product indicates that TVCA4 is expressed. RNA expression of the Trichomonas ATPases, except TVCA3, was constitutive over a range of environmental conditions. TVCA1, TVAPLT3 and TVPATP8 had the highest levels of RNA expression while TVAPLT1 and TVAPLT2 expression was the lowest.