title: Bacterial chemoreceptor dynamics correlate with activity state and are coupled over long distances.
abstract: Dynamics are hypothesized to play an important role in the transmission of signals across membranes by receptors. Bacterial chemoreceptors are long helical proteins that consist of a periplasmic ligand-binding domain; a transmembrane region; a cytoplasmic HAMP (histidine kinase, adenylyl cyclases, methyl-accepting chemotaxis proteins, and phosphatases) domain; and a kinase-control module (KCM). The KCM is further composed of adaptation, hinge, and protein interaction regions (PIRs), the latter of which binds the histidine kinase CheA and adaptor CheW. Fusions of the Escherichia coli aspartate receptor KCM to HAMP domains of defined structure (H1-Tar vs. H1-2-Tar) give opposite responses in phosphotransfer and cellular assays, despite similar binding to CheA and CheW. Pulsed dipolar ESR spectroscopy (PDS) of these isolated on and off dimeric effectors reveals that, in the kinase-on state, the HAMP is more conformationally destabilized compared with the PIR, whereas in the kinase-off state, the HAMP is more compact, and the PIR samples a greater breadth of conformations. On and off HAMP states produce different conformational effects at the KCM junction, but these differences decrease through the adaptation region and into the hinge only to return with the inverted relationship in the PIR. Continuous wave-ESR of the spin-labeled proteins confirms that broader PDS distance distributions correlate with increased rates of dynamics. Conformational breadth in the adaptation region changes with charge alterations caused by modification enzymes. Activating modifications broaden the HAMP conformational ensemble but correspondingly, compact the PIR. Thus, chemoreceptors behave as coupled units, in which dynamics in regions proximal and distal to the membrane change coherently but with opposite sign.
authors: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853; and National Biomedical Center for Advanced ESR Technologies, Cornell University, Ithaca NY 14853.
authors: Dipanjan
authors: D
authors: Samanta
authors: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853; and National Biomedical Center for Advanced ESR Technologies, Cornell University, Ithaca NY 14853.
authors: Peter P
authors: PP
authors: Borbat
authors: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853; and National Biomedical Center for Advanced ESR Technologies, Cornell University, Ithaca NY 14853.
authors: Boris
authors: B
authors: Dzikovski
authors: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853; and National Biomedical Center for Advanced ESR Technologies, Cornell University, Ithaca NY 14853.
authors: Jack H
authors: JH
authors: Freed
authors: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853; and bc69@cornell.edu.
authors: Brian R
authors: BR
authors: Crane
mesh_terms: D000494:Allosteric Regulation; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D000071677:Histidine Kinase; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D008958:Models, Molecular; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D013113:Spin Labels
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D011993:Recombinant Fusion Proteins; D013113:Spin Labels; D000071677:Histidine Kinase; C000607608:cheA protein, E coli
keywords: adaptation; allostery; chemotaxis; dynamics; transmembrane signaling receptor