title: Polar localization of CheA2 in Rhodobacter sphaeroides requires specific Che homologs.
abstract: Rhodobacter sphaeroides is a motile bacterium that has multiple chemotaxis genes organized predominantly in three major operons (cheOp(1), cheOp(2), and cheOp(3)). The chemoreceptor proteins are clustered at two distinct locations, the cell poles and in one or more cytoplasmic clusters. One intriguing possibility is that the physically distinct chemoreceptor clusters are each composed of a defined subset of specific chemotaxis proteins, including the chemoreceptors themselves plus specific CheW and CheA proteins. Here we report the subcellular localization of one such protein, CheA(2), under aerobic and photoheterotrophic growth conditions. CheA(2) is predominantly clustered and localized at the cell poles under both growth conditions. Furthermore, its localization is dependent upon one or more genes in cheOp(2) but not those of cheOp(1) or cheOp(3). In E. coli, the polar localization of CheA depends upon CheW. The R. sphaeroides cheOp(2) contains two cheW genes. Interestingly, CheW(2) is required under both aerobic and photoheterotrophic conditions, whereas CheW(3) is not required under aerobic conditions but appears to play a modest role under photoheterotrophic conditions. This suggests that R. sphaeroides contains at least two distinct chemotaxis complexes, possibly composed of proteins dedicated for each subcellular location. Furthermore, the composition of these spatially distinct complexes may change under different growth conditions.
authors.affiliation: Microbiology Unit, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom.
authors.forename: Angela C
authors.initials: AC
authors.lastname: Martin
authors.forename: Usha
authors.initials: U
authors.lastname: Nair
authors.forename: Judith P
authors.initials: JP
authors.lastname: Armitage
authors.forename: Janine R
authors.initials: JR
authors.lastname: Maddock
mesh_terms: D000332:Aerobiosis; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D016764:Cell Polarity; D002633:Chemotaxis; D003470:Culture Media; D029968:Escherichia coli Proteins; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D000071677:Histidine Kinase; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D012242:Rhodobacter sphaeroides / Q000235:genetics / Q000254:growth & development / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C051236:CheW protein, Bacteria; D000071677:Histidine Kinase; C000607608:cheA protein, E coli