title: Arginine transport in Streptococcus lactis is catalyzed by a cationic exchanger.
abstract: Streptococcus lactis metabolizes arginine via the arginine deiminase pathway to ornithine, CO2, NH3, and ATP. The translocation of arginine and ornithine has been studied using membrane vesicles of galactose/arginine-grown cells of S. lactis fused with cytochrome c oxidase proteoliposomes by the freeze/thaw--sonication procedure earlier described. In the presence of reduced cytochrome c the fused membranes rapidly accumulate ornithine. Addition of arginine releases accumulated ornithine. Rapid uncoupler-insensitive exchange between external arginine and internal ornithine is seen at rates that are at least 60-fold higher than the rate of protonmotive force-driven arginine translocation. This arginine:ornithine exchange activity was reconstituted in proteoliposomes after solubilization of S. lactis membranes with octyl beta-D-glucopyranoside. These proteoliposomes catalyze a one-to-one exchange between arginine and ornithine. The arginine:ornithine exchange system is the first exchange system for cationic metabolites found in bacteria. Translocation of arginine via this system does not require metabolic energy obtained by arginine metabolism.
authors.forename: A J
authors.initials: AJ
authors.lastname: Driessen
authors.forename: B
authors.initials: B
authors.lastname: Poolman
authors.forename: R
authors.initials: R
authors.lastname: Kiewiet
authors.forename: W
authors.initials: W
authors.lastname: Konings
mesh_terms: D017920:Antiporters; D001120:Arginine / Q000378:metabolism*; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism; D007474:Ion Exchange; D007700:Kinetics; D013294:Lactococcus lactis / Q000378:metabolism*; D008081:Liposomes; D009952:Ornithine / Q000378:metabolism
chemical_list: D017920:Antiporters; D002352:Carrier Proteins; D008081:Liposomes; D001120:Arginine; D009952:Ornithine