The research described in this project is designed to ask and provide answers to basic questions about the structure and functions of the outer membrane of Gram-negative bacteria. Specifically, it will yield knowledge about membrane protein tertiary and quaternary structure, provide specific information about how an important class of transmembrane proteins (the porins) form hydrophilic channels through the membrane, and give insights into the relationships between the various components of the outer membrane. Gram-negative bacteria are important enteric and systemic pathogens. The outer membrane and its related structure play key roles in colonization, immunogenicity, viability and the antibiotic response of these organisms. A better knowledge of the structure and function of the outer membrane will aid in the development of antibiotics and treatments for pathological conditions caused by these organisms. The main thrust of the proposed research is the in-depth use of genetic and biochemical approaches to isolate and characterize Escherichia coli mutants which have specific altered properties of the outer membrane. One approach that will be used is to select for the uptake of substrates which normally do not traverse the outer membrane barrier. This selection yields mutants which have altered porin proteins. These alterations impart a hypersensitivity to detergents and antibiotics. The hyperpermeable mutants will be analyzed phenotypically and the exact nature of the lesions in the gene for the porin proteins will be determined at the DNA level. The hyperpermeability phenotype exhibited by these mutants will be used to develop additional selections for the isolation of novel mutants which have acquired regulatory or compensatory mutations which reduce or eliminate the hyperpermeability phenotype. The genetically and biochemically analysis of the many mutant types isolated in this project will help to achieve the goals of the project.
| Sampson, B A; Misra, R; Benson, S A (1989) Identification and characterization of a new gene of Escherichia coli K-12 involved in outer membrane permeability. Genetics 122:491-501 |
| Misra, R; Benson, S A (1989) A novel mutation, cog, which results in production of a new porin protein (OmpG) of Escherichia coli K-12. J Bacteriol 171:4105-11 |
| Benson, S A; Occi, J L; Sampson, B A (1988) Mutations that alter the pore function of the OmpF porin of Escherichia coli K12. J Mol Biol 203:961-70 |
| Misra, R; Benson, S A (1988) Isolation and characterization of OmpC porin mutants with altered pore properties. J Bacteriol 170:528-33 |
| Misra, R; Benson, S A (1988) Genetic identification of the pore domain of the OmpC porin of Escherichia coli K-12. J Bacteriol 170:3611-7 |
