Transmembrane signaling characterized in bacterial chemoreceptors by using sulfhydryl cross-linking in vivo.
Transmembrane signaling by bacterial chemoreceptors is thought to involve conformational changes within a stable homodimer. We investigated the functional consequences of constraining movement between pairs of helices in the four-helix structure of the transmembrane domain of chemoreceptor Trg. Using a family of cysteine-containing receptors, we identified oxidation treatments for intact cells that catalyzed essentially complete sulfhydryl cross-linking at selected positions and yet left flagellar and sensory functions largely unperturbed. Constraining movement by cross-links between subunits had little effect on tactic response, but constraining movement between transmembrane segments of the monomer drastically reduced function. We deduce that transmembrane signaling requires substantial movement between transmembrane helices of a monomer but not between interacting helices across the interface between subunits.
Lee
G F
GF
Department of Biochemistry and Biophysics, Washington State University, Pullman 99164-4660, USA.
Lebert
M R
MR
Lilly
A A
AA
Hazelbauer
G L
GL
D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D002633:Chemotaxis / Q000502:physiology*; D003432:Cross-Linking Reagents; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology*; D029968:Escherichia coli Proteins; D005407:Flagella / Q000502:physiology; D008565:Membrane Proteins; D008958:Models, Molecular; D009068:Movement; D010084:Oxidation-Reduction; D011487:Protein Conformation; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000502:physiology*; D012266:Ribose / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology*; D013438:Sulfhydryl Compounds
D001426:Bacterial Proteins; D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D013438:Sulfhydryl Compounds; C041476:Trg protein, E coli; D012266:Ribose