3zx6
From Proteopedia
Structure of Hamp(AF1503)-Tsr fusion - Hamp (A291V) mutant
Structural highlights
FunctionO28769_ARCFU MCP1_ECOLI Receptor for the attractant L-serine and related amino acids. Is also responsible for chemotaxis away from a wide range of repellents, including leucine, indole, and weak acids. Chemotactic-signal transducers respond to changes in the concentration of attractants and repellents in the environment, transduce a signal from the outside to the inside of the cell, and facilitate sensory adaptation through the variation of the level of methylation. Attractants increase the level of methylation while repellents decrease the level of methylation, the methyl groups are added by the methyltransferase CheR and removed by the methylesterase CheB. Publication Abstract from PubMedBacterial chemotaxis receptors are elongated homodimeric coiled-coil bundles, which transduce signals generated in an N-terminal sensor domain across 15-20nm to a conserved C-terminal signaling subdomain. This signal transduction regulates the activity of associated kinases, altering the behavior of the flagellar motor and hence cell motility. Signaling is in turn modulated by selective methylation and demethylation of specific glutamate and glutamine residues in an adaptation subdomain. We have determined the structure of a chimeric protein, consisting of the HAMP domain from Archaeoglobus fulgidus Af1503 and the methyl-accepting domain of Escherichia coli Tsr. It shows a 21nm coiled coil that alternates between two coiled-coil packing modes: canonical knobs-into-holes and complementary x-da, a variant form related to the canonical one by axial rotation of the helices. Comparison of the obtained structure to the Thermotoga maritima chemoreceptor TM1143 reveals that they adopt different axial rotation states in their adaptation subdomains. This conformational change is presumably induced by the upstream HAMP domain and may modulate the affinity of the chemoreceptor to the methylation-demethylation system. The presented findings extend the cogwheel model for signal transmission to chemoreceptors. Axial helix rotation as a mechanism for signal regulation inferred from the crystallographic analysis of the E. coli serine chemoreceptor.,Ferris HU, Zeth K, Hulko M, Dunin-Horkawicz S, Lupas AN J Struct Biol. 2014 Mar 27. pii: S1047-8477(14)00068-9. doi:, 10.1016/j.jsb.2014.03.015. PMID:24680785[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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