| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA
2 Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, USA
3 Departments of Chemistry and Pharmacology and the Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235-1822, USA
Reprint requests to: Gerald L. Hazelbauer, Department of Biochemistry, University of Missouri-Columbia, 117 Schweitzer Hall, Columbia, MO 65211; e-mail: hazelbauerg{at}missouri.edu; fax: (573) 882-5635.
Bacterial chemoreceptors signal across the membrane by conformational changes that traverse a four-helix transmembrane domain. High-resolution structures are available for the chemoreceptor periplasmic domain and part of the cytoplasmic domain but not for the transmembrane domain. Thus, we constructed molecular models of the transmembrane domains of chemoreceptors Trg and Tar, using coordinates of an unrelated four-helix coiled coil as a template and the X-ray structure of a chemoreceptor periplasmic domain to establish register and positioning. We tested the models using the extensive data for cross-linking propensities between cysteines introduced into adjacent transmembrane helices, and we found that many aspects of the models corresponded with experimental observations. The one striking disparity, the register of transmembrane helix 2 (TM2) relative to its partner transmembrane helix 1, could be corrected by sliding TM2 along its long axis toward the periplasm. The correction implied that axial sliding of TM2, the signaling movement indicated by a large body of data, was of greater magnitude than previously thought. The refined models were used to assess effects of inter-helical disulfides on the two ligand-induced conformational changes observed in alternative crystal structures of periplasmic domains: axial sliding within a subunit and subunit rotation. Analyses using a measure of disulfide potential energy provided strong support for the helical sliding model of transmembrane signaling but indicated that subunit rotation could be involved in other ligand-induced effects. Those analyses plus modeled distances between diagnostic cysteine pairs indicated a magnitude for TM2 sliding in transmembrane signaling of several angstroms.
Keywords: Bacterial chemotaxis; transmembrane receptors; conformational change; molecular modeling
CiteULike 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
 |
|
  D. N. Amin, B. L. Taylor, and M. S. Johnson Organization of the Aerotaxis Receptor Aer in the Membrane of Escherichia coli J. Bacteriol., October 15, 2007; 189(20): 7206 - 7212. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Gao and D. G. Lynn Integration of Rotation and Piston Motions in Coiled-Coil Signal Transduction J. Bacteriol., August 15, 2007; 189(16): 6048 - 6056. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W.-C. Lai, M. L. Peach, T. P. Lybrand, and G. L. Hazelbauer Diagnostic cross-linking of paired cysteine pairs demonstrates homologous structures for two chemoreceptor domains with low sequence identity Protein Sci., January 1, 2006; 15(1): 94 - 101. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Boldog and G. L. Hazelbauer Accessibility of introduced cysteines in chemoreceptor transmembrane helices reveals boundaries interior to bracketing charged residues Protein Sci., June 1, 2004; 13(6): 1466 - 1475. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. A. Appleman, L.-L. Chen, and V. Stewart Probing Conservation of HAMP Linker Structure and Signal Transduction Mechanism through Analysis of Hybrid Sensor Kinases J. Bacteriol., August 15, 2003; 185(16): 4872 - 4882. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Barnakov, C. Altenbach, L. Barnakova, W. L. Hubbell, and G. L. Hazelbauer Site-directed spin labeling of a bacterial chemoreceptor reveals a dynamic, loosely packed transmembrane domain Protein Sci., June 1, 2002; 11(6): 1472 - 1481. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
