The Bacillus subtilis cysP gene encodes a novel sulphate permease related to the inorganic phosphate transporter (Pit) family

Sulphate permeases in the plasma membrane are responsible for uptake of env ironmental sulphate used in the sulphate assimilation pathway in bacteria a nd plants. Here it is reported that the ORF designated cysP. located on the Bacillus subtilis chromosome between cysH and five putative genes involved in sulphate assimilation, encodes a sulphate permease. cysP is able to com plement Escherichia coli cysteine auxotrophs with mutations affecting eithe r the membrane or periplasmic components of the sulphate-thiosulphate perme ase. Transport studies with cell suspensions of a cysA97 E. coli strain tra nsformed with a plasmid expressing the B. subtilis cysP gene indicated that CysP catalyses sulphate uptake. Analysis of the primary sequence showed th at CysP (354 amino acids, estimated molecular mass 24 kDa) is a highly hydr ophobic protein which has 11 putative transmembrane helices. Sequence compa risons revealed that CysP. together with the phosphate permease of Neurospo ra crassa, Pho-4. and E. coli PitA. belongs to the family of related transp orters, the inorganic phosphate transporter (Pit) family. Among the putativ e phosphate permeases. CysP shows a similar size and the same domain organi zation as the archaeal transporters. This is the first report: of a sulphat e permease in a Gram-positive organism.