The Structure of a Soluble Chemoreceptor Suggests a Mechanism for Propagating Conformational Signals

Journal Article · Wed Sep 02 04:00:00 EDT 2009 · Biochemistry-US

DOI:https://doi.org/10.1021/bi801727m· OSTI ID:1005782

Pollard, Abiola M; Bilwes, Alexandrine M; Crane, Brian R; Cornell,

Transmembrane chemoreceptors, also known as methyl-accepting chemotaxis proteins (MCPs), translate extracellular signals into intracellular responses in the bacterial chemotaxis system. MCP ligand binding domains control the activity of the CheA kinase, situated {approx}200 {angstrom} away, across the cytoplasmic membrane. The 2.17 {angstrom} resolution crystal structure of a Thermotoga maritima soluble receptor (Tm14) reveals distortions in its dimeric four-helix bundle that provide insight into the conformational states available to MCPs for propagating signals. A bulge in one helix generates asymmetry between subunits that displaces the kinase-interacting tip, which resides more than 100 {angstrom} away. The maximum bundle distortion maps to the adaptation region of transmembrane MCPs where reversible methylation of acidic residues tunes receptor activity. Minor alterations in coiled-coil packing geometry translate the bulge distortion to a >25 {angstrom} movement of the tip relative to the bundle stalks. The Tm14 structure discloses how alterations in local helical structure, which could be induced by changes in methylation state and/or by conformational signals from membrane proximal regions, can reposition a remote domain that interacts with the CheA kinase.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE
• OSTI ID: 1005782
• Journal Information: Biochemistry-US, Journal Name: Biochemistry-US Journal Issue: (9) ; 03, 2009 Vol. 48; ISSN 0006-2960; ISSN BICHAW
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
ASYMMETRY
CHEMORECEPTORS
CRYSTAL STRUCTURE
GEOMETRY
MEMBRANES
METHYLATION
PROTEINS
RESIDUES
RESOLUTION