title: CryoEM and computer simulations reveal a novel kinase conformational switch in bacterial chemotaxis signaling.
abstract: Chemotactic responses in bacteria require large, highly ordered arrays of sensory proteins to mediate the signal transduction that ultimately controls cell motility. A mechanistic understanding of the molecular events underlying signaling, however, has been hampered by the lack of a high-resolution structural description of the extended array. Here, we report a novel reconstitution of the array, involving the receptor signaling domain, histidine kinase CheA, and adaptor protein CheW, as well as a density map of the core-signaling unit at 11.3 Å resolution, obtained by cryo-electron tomography and sub-tomogram averaging. Extracting key structural constraints from our density map, we computationally construct and refine an atomic model of the core array structure, exposing novel interfaces between the component proteins. Using all-atom molecular dynamics simulations, we further reveal a distinctive conformational change in CheA. Mutagenesis and chemical cross-linking experiments confirm the importance of the conformational dynamics of CheA for chemotactic function.
authors.affiliation: Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, United States.
authors.forename: C Keith
authors.initials: CK
authors.lastname: Cassidy
authors.affiliation: Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Himes
authors.affiliation: Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States.
authors.forename: Frances J
authors.initials: FJ
authors.lastname: Alvarez
authors.affiliation: Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States.
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.affiliation: Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States.
authors.forename: Gongpu
authors.initials: G
authors.lastname: Zhao
authors.affiliation: Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, United States.
authors.forename: Juan R
authors.initials: JR
authors.lastname: Perilla
authors.affiliation: Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, United States.
authors.forename: Klaus
authors.initials: K
authors.lastname: Schulten
authors.affiliation: Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States.
authors.forename: Peijun
authors.initials: P
authors.lastname: Zhang
keywords: E. coli; biophysics; computational biology; structural biology; systems biology