title: Bacterial chemoreceptor arrays are hexagonally packed trimers of receptor dimers networked by rings of kinase and coupling proteins.
abstract: Chemoreceptor arrays are supramolecular transmembrane machines of unknown structure that allow bacteria to sense their surroundings and respond by chemotaxis. We have combined X-ray crystallography of purified proteins with electron cryotomography of native arrays inside cells to reveal the arrangement of the component transmembrane receptors, histidine kinases (CheA) and CheW coupling proteins. Trimers of receptor dimers lie at the vertices of a hexagonal lattice in a "two-facing-two" configuration surrounding a ring of alternating CheA regulatory domains (P5) and CheW couplers. Whereas the CheA kinase domains (P4) project downward below the ring, the CheA dimerization domains (P3) link neighboring rings to form an extended, stable array. This highly interconnected protein architecture underlies the remarkable sensitivity and cooperative nature of transmembrane signaling in bacterial chemotaxis.
authors.affiliation: Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
authors.forename: Ariane
authors.initials: A
authors.lastname: Briegel
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Li
authors.forename: Alexandrine M
authors.initials: AM
authors.lastname: Bilwes
authors.forename: Kelly T
authors.initials: KT
authors.lastname: Hughes
authors.forename: Grant J
authors.initials: GJ
authors.lastname: Jensen
authors.forename: Brian R
authors.initials: BR
authors.lastname: Crane
mesh_terms: D001412:Bacillus subtilis / Q000378:metabolism; D018407:Bacterial Physiological Phenomena; D001426:Bacterial Proteins / Q000737:chemistry*; D002628:Chemoreceptor Cells / Q000166:cytology*; D002633:Chemotaxis; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods; D003593:Cytoplasm / Q000378:metabolism; D019281:Dimerization; D055032:Electron Microscope Tomography / Q000379:methods; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry*; D000071677:Histidine Kinase; D008565:Membrane Proteins / Q000737:chemistry*; D000072236:Methyl-Accepting Chemotaxis Proteins; D011485:Protein Binding; D011487:Protein Conformation; D019779:Salmonella enterica / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C489103:CheW protein, E coli; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D000071677:Histidine Kinase; C000607608:cheA protein, E coli