Transport of molecules across biological membranes is a fundamental process shared by all living cells. In Gram-negative bacteria, such as Escherichia coil, transport occurs across two membranes, of which the outer membrane represents the first permeability barrier. Outer membrane protein-mediated transport is needed to bring nutrients inside and expel unwanted metabolites and inhibitors. Ironically, toxic biomolecules and infectious agents, present in the hostile environment in which bacteria live, frequently exploit these outer membrane proteins to gain entry into the cell. The focus of this research is a unique outer membrane protein, TolC, which mediates the diffusion of a diverse group of molecules including the export of alpha-hemolysin and the efflux of antibiotics. Despite the resolution of TolC's three-dimensional structure, the role of individual residues and the mechanism by which it accomplishes the transport of a diverse group of molecules remains poorly understood. Moreover, it is unknown how TolC interacts with other proteins of the inner membrane to form the complexes that facilitate the two-way transport activity. The present study is being undertaken to examine the role of TolC in export (antibiotic) and import (colicin E1 ), as well as to examine its interactions with other proteins of the transport complexes. Identification of functionally critical TolC residues and the various protein-protein interactions that must occur to accomplish the diverse transport activities will be achieved through employing a combination of genetic, structural, and biochemical approaches; available preliminary data concerning all aspects of the project strongly reflect their feasibility.The presence of TolC and its homologues in other Gram-negative bacteria demonstrates the broader relevance of this unique multifunctional protein. Besides the obvious role of TolC in antibiotic resistance, its ability to mediate the secretion of a variety of virulence factors in pathogenic bacteria makes it a medically important subject of investigation.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM066988-02
Application #
6785828
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Program Officer
Chin, Jean
Project Start
2003-08-05
Project End
2007-07-31
Budget Start
2004-08-01
Budget End
2005-07-31
Support Year
2
Fiscal Year
2004
Total Cost
$213,034
Indirect Cost
Name
Arizona State University-Tempe Campus
Department
Microbiology/Immun/Virology
Type
Schools of Arts and Sciences
DUNS #
943360412
City
Tempe
State
AZ
Country
United States
Zip Code
85287
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