title: Attractant signaling by an aspartate chemoreceptor dimer with a single cytoplasmic domain.
abstract: Signal transduction across cell membranes often involves interactions among identical receptor subunits, but the contribution of individual subunits is not well understood. The chemoreceptors of enteric bacteria mediate attractant responses by interrupting a phosphotransfer circuit initiated at receptor complexes with the protein kinase CheA. The aspartate receptor (Tar) is a homodimer, and oligomerized cytoplasmic domains stimulate CheA activity much more than monomers do in vitro. Intragenic complementation was used to show in Escherichia coli that heterodimers containing one full-length and one truncated Tar subunit mediated responses to aspartate in the presence of full-length Tar homodimers that could not bind aspartate. Thus, a Tar dimer containing only one cytoplasmic domain can initiate an attractant (inhibitory) signal, although it may not be able to stimulate kinase activity of CheA.
authors.affiliation: Department of Biology, Texas A&M University, College Station, TX 77840, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Gardina
authors.forename: M D
authors.initials: MD
authors.lastname: Manson
mesh_terms: D001224:Aspartic Acid / Q000378:metabolism* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002628:Chemoreceptor Cells; D002633:Chemotaxis; D003593:Cytoplasm / Q000378:metabolism; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D029968:Escherichia coli Proteins; D005816:Genetic Complementation Test; D000071677:Histidine Kinase; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D009154:Mutation; D010957:Plasmids; D011487:Protein Conformation; D011494:Protein Kinases / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D011956:Receptors, Cell Surface; C057331:Tar protein, E coli; D001224:Aspartic Acid; D011494:Protein Kinases; D000071677:Histidine Kinase; C000607608:cheA protein, E coli