ATP-driven calcium transport in membrane vesicles of Streptococcus sanguis

Calcium transport was investigated in membrane vesicles prepared from the oral bacterium Streptococcus sanguis. Procedures were devised for the preparation of membrane vesicles capable of accumulating 45Ca2+. Uptake was ATP dependent and did not require a proton motive force. Calcium transport in these vesicles was compared with 45Ca2+ accumulation in membrane vesicles from Streptococcus faecalis and Escherichia coli. The data support the existence of an ATP-driven calcium pump in S. sanguis similar to that in S. faecalis. This pump, which catalyzes uptake into membrane vesicles, would be responsible for extrusion of calcium from intact cells.