Molecular cloning of a P-type ATPase gene from the cyanobacterium Synechocystis sp. PCC 6803. Homology to eukaryotic Ca(2+)-ATPases

Abstract

With oligonucleotide primers derived from P-type ATPase genes of different sources, a part of Synechocystis sp. PCC 6803 genomic DNA was amplified and used as hybridization probe for the Synechocystis gene. A 4.7 kb HindIII fragment was cloned and sequenced; it contains the open reading frame of the E1E2-ATPase. The Synechocystis ATPase (named PMA1) consists of 915 amino acids with a M(r) of 98,902; it has ten putative transmembrane domains and contains the conserved regions a to j common to all P-type ATPases. Its amino acid sequence shows less than 20% identity to prokaryotic ATPases but about 30% identity to eukaryotic Ca(2+)-ATPases. An alignment to rat kidney and yeast Ca(2+)-ATPase protein sequences shows homology in stalk regions and transmembrane domains domains which are thought to be involved in calcium binding and transport; these three ATPases reveal very similar hydropathy plots and form a separate group in the phylogenetic tree of P-type ATPases. The results strongly support the assumption that PMA1 of Synechocystis is a calcium translocating ATPase, possibly involved in regulatory processes with calcium as second messenger.