title: Activated chemoreceptor arrays remain intact and hexagonally packed.
abstract: Bacterial chemoreceptors cluster into exquisitively sensitive, tunable, highly ordered, polar arrays. While these arrays serve as paradigms of cell signalling in general, it remains unclear what conformational changes transduce signals from the periplasmic tips, where attractants and repellents bind, to the cytoplasmic signalling domains. Conflicting reports support and contest the hypothesis that activation causes large changes in the packing arrangement of the arrays, up to and including their complete disassembly. Using electron cryotomography, here we show that in Caulobacter crescentus, chemoreceptor arrays in cells grown in different media and immediately after exposure to the attractant galactose all exhibit the same 12 nm hexagonal packing arrangement, array size and other structural parameters. ΔcheB and ΔcheR mutants mimicking attractant- or repellent-bound states prior to adaptation also show the same lattice structure. We conclude that signal transduction and amplification must be accomplished through only small, nanoscale conformational changes.
authors: Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
authors: Ariane
authors: A
authors: Briegel
authors: Morgan
authors: M
authors: Beeby
authors: Martin
authors: M
authors: Thanbichler
authors: Grant J
authors: GJ
authors: Jensen
mesh_terms: D016935:Caulobacter crescentus / Q000737:chemistry* / Q000378:metabolism*; D020285:Cryoelectron Microscopy; D055032:Electron Microscope Tomography; D005690:Galactose / Q000378:metabolism; D017353:Gene Deletion; D046911:Macromolecular Substances / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D015398:Signal Transduction
chemical_list: D046911:Macromolecular Substances; D008565:Membrane Proteins; D005690:Galactose