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 gone. A 4·7 kb HindIII fragment was cloned and sequenced; it contains the open reading frame of the E 1E 2-ATPase. The Synechocystis ATPase (named PM A1) 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 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 PM A1 of Synechocystis is a calcium translocating ATPase, possibly involved in regulatory processes with calcium as second messenger.