title: Determinants of chemoreceptor cluster formation in Escherichia coli.
abstract: Chemotactic stimuli in bacteria are sensed by large sensory complexes, or receptor clusters, that consist of tens of thousands of proteins. Receptor clusters appear to play a key role in signal processing, but their structure remains poorly understood. Here we used fluorescent protein fusions to study in vivo formation of the cluster core, which consists of receptors, a kinase CheA and an assisting protein CheW. We show that receptors aggregate through their cytoplasmic domains even in the absence of other chemotaxis proteins. Clustering is further enhanced by the binding of CheW. Surprisingly, we observed that some fragments of CheA bind receptor clusters well in the absence of CheW, although the latter does assist the binding of full-length CheA. The resulting mode of receptor cluster formation is consistent with an experimentally observed flexible stoichiometry of chemosensory complexes and with assumptions of recently proposed computer models of signal processing in chemotaxis.
authors.affiliation: Zentrum für Molekulare Biologie der Universität Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Kentner
authors.forename: Sebastian
authors.initials: S
authors.lastname: Thiem
authors.forename: Markus
authors.initials: M
authors.lastname: Hildenbeutel
authors.forename: Victor
authors.initials: V
authors.lastname: Sourjik
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002628:Chemoreceptor Cells / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D000071677:Histidine Kinase; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D008780:Methyltransferases / Q000235:genetics; D046912:Multiprotein Complexes; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; C489103:CheW protein, E coli; D029968:Escherichia coli Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D046912:Multiprotein Complexes; D011993:Recombinant Fusion Proteins; C054562:yellow fluorescent protein, Bacteria; C513923:CheR protein, E coli; D008780:Methyltransferases; D000071677:Histidine Kinase; C000607608:cheA protein, E coli