THE PACL GENE OF SYNECHOCOCCUS SP STRAIN PCC-7942 ENCODES A CA2-TRANSPORTING ATPASE()

An ATP-dependent Ca2+ uptake activity was identified in plasma membran e vesicles prepared from Synechococcus sp. strain PCC 7942. This activ ity was insensitive to agents which collapse DB gradients and membrane potentials but sensitive to vanadate, indicating that the activity is catalyzed by a P-type Ca2+-ATPase. A gene was cloned from Synechococc us sp. strain PCC 7942 by using a degenerate oligonucleotide based on a sequence conserved among P-type ATPases. This gene (pacL) encodes a product similar in structure to eukaryotic Ca2+-ATPases. We have shown that pacl encodes a Ca2+-ATPase by demonstrating that a strain in whi ch pact is disrupted has no Ca2+-ATPase activity associated with its p lasma membrane. In addition, Ca2+-ATPase activity was restored to the Delta pacL strain by introducing pact into a second site in the Synech ococcus sp. strain PCC 7942 chromosome.