Studies are proposed of the aspartate and serine receptor proteins from the Escherichia coli chemotaxis pathway, and of the cytoplasmic signalling proteins with which they interact, regarding issues of linkage, cooperativity, conformational change and clustering using quantitative thermodynamic (isothermal titration calorimetry) and spectroscopic methods (Fluorescence and EPR) with biochemical assays of signalling activity. A feature of many transmembrane receptors is the dimeric, or more generally oligomeric, organization of binding permits the system to exhibit cooperativity and linkage phenomena that have important consequences for many membrane phenomena. Under physiological conditions it is not understood the extent to which transmembrane signalling occurs by changes in receptor clustering, through conformational changes within stable clusters of receptor, or both. These issues could be resolved if more information were available about the conformational changes, the clustering reactions, and the mutual influence of ligands binding on opposite sides of the membrane (transbilayer binding effects). It is proposed that this information will be obtained through (i) precise measurements of the thermodynamic and kinetic parameters that characterize ligand binding, domain interaction and subunit interaction of membrane proteins, (ii) accurate and sensitive spectroscopic methods to determine changes in receptor conformation and dynamics in response to ligand binding and protein-protein interactions, and (iii) localization of the sites of interaction between signalling proteins. Completion of the proposed studies will give a complete picture of the physical mechanism of transmembrane signalling and the molecular mechanism of receptor desensitization by covalent modification. The bacterial chemotaxis pathway belongs to the superfamily of two-component signalling systems that have been found in prokaryotes, eukaryotic microorganisms and plants. The information should thus be of widespread fundamental significance, and also directly relevant to understanding signal transduction processes in pathogenic microbes.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM053210-03
Application #
2857227
Study Section
Biophysical Chemistry Study Section (BBCB)
Project Start
1997-01-01
Project End
2000-12-31
Budget Start
1999-01-01
Budget End
2000-12-31
Support Year
3
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of Massachusetts Amherst
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
153223151
City
Amherst
State
MA
Country
United States
Zip Code
01003
Fowler, Daniel J; Weis, Robert M; Thompson, Lynmarie K (2010) Kinase-active signaling complexes of bacterial chemoreceptors do not contain proposed receptor-receptor contacts observed in crystal structures. Biochemistry 49:1425-34
Besschetnova, Tatiana Y; Montefusco, David J; Asinas, Abdalin E et al. (2008) Receptor density balances signal stimulation and attenuation in membrane-assembled complexes of bacterial chemotaxis signaling proteins. Proc Natl Acad Sci U S A 105:12289-94
Montefusco, David J; Asinas, Abdalin E; Weis, Robert M (2007) Liposome-mediated assembly of receptor signaling complexes. Methods Enzymol 423:267-98
Montefusco, David J; Shrout, Anthony L; Besschetnova, Tatiana Y et al. (2007) Formation and activity of template-assembled receptor signaling complexes. Langmuir 23:3280-9
Asinas, Abdalin E; Weis, Robert M (2006) Competitive and cooperative interactions in receptor signaling complexes. J Biol Chem 281:30512-23
Chalah, Anas; Weis, Robert M (2005) Site-specific and synergistic stimulation of methylation on the bacterial chemotaxis receptor Tsr by serine and CheW. BMC Microbiol 5:12
Weis, Robert M; Hirai, Teruhisa; Chalah, Anas et al. (2003) Electron microscopic analysis of membrane assemblies formed by the bacterial chemotaxis receptor Tsr. J Bacteriol 185:3636-43
Shrout, Anthony L; Montefusco, David J; Weis, Robert M (2003) Template-directed assembly of receptor signaling complexes. Biochemistry 42:13379-85
Nunez, M E; Noyes, K T; Gianolio, D A et al. (2000) Long-range guanine oxidation in DNA restriction fragments by a triplex-directed naphthalene diimide intercalator. Biochemistry 39:6190-9
Li, G; Weis, R M (2000) Covalent modification regulates ligand binding to receptor complexes in the chemosensory system of Escherichia coli. Cell 100:357-65

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