Unique structural features in the periplasmic binding proteins and in the lactose and trp repressors from E. coli will be explored using the method of site-directed mutagenesis to generate proteins with specific alterations at desired points in the primary sequence of the protein. These proteins play significant non-enzymatic roles in the bacterial cell. Detailed three-dimensional structural data are available for the arabinose binding protein. Based on primary sequence homology with arabinose binding protein, a sugar binding site for the lactose represssor protein has been predicted, and a region with homology to DNA binding sites in other represssors has been found for both lac and trp repressors. The mutant proteins produced will be isolated in large quantities and characterized extensively with regard to their properties, including both equilibrium and kinetic measurements of binding, spectroscopic analysis, and chemical reactivity of selected amino acids. Selection of sites for mutagenesis will be based on the 3-dimensional structure of the binding protein and on sugar and DNA binding site homology with proteins of known structure for the repressors. Efforts will be directed toward changes in the binding sites of all the proteins, in the hinge region between the two domains found in the binding protein, and in the contact areas between these domains. The specific amino acid changes generated will be based on anticipated interesting alterations in the protein structure/function; the predicted changes will be compared to the experimental results. Crystallization of the mutant proteins (including lac repressor) will be attempted in order to directly compare structural differences with the parent wild-type protein. The combination of structural and functional data from this range of different proteins will be useful in determining the effects of specific amino acid changes on the folding patterns and chemistry of binding for these proteins.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM035133-02
Application #
3287297
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1985-08-30
Project End
1988-07-31
Budget Start
1986-08-01
Budget End
1987-07-31
Support Year
2
Fiscal Year
1986
Total Cost
Indirect Cost
Name
Rice University
Department
Type
Schools of Arts and Sciences
DUNS #
050299031
City
Houston
State
TX
Country
United States
Zip Code
77005
Chakerian, A E; Matthews, K S (1992) Effect of lac repressor oligomerization on regulatory outcome. Mol Microbiol 6:963-8
Chakerian, A E; Matthews, K S (1991) Characterization of mutations in oligomerization domain of Lac repressor protein. J Biol Chem 266:22206-14
Spotts, R O; Chakerian, A E; Matthews, K S (1991) Arginine 197 of lac repressor contributes significant energy to inducer binding. Confirmation of homology to periplasmic sugar binding proteins. J Biol Chem 266:22998-3002
He, J J; Matthews, K S (1990) Effect of amino acid alterations in the tryptophan-binding site of the trp repressor. J Biol Chem 265:731-7
Chou, W Y; Matthews, K S (1989) Serine to cysteine mutations in trp repressor protein alter tryptophan and operator binding. J Biol Chem 264:18314-9
Chou, W Y; Bieber, C; Matthews, K S (1989) Tryptophan and 8-anilino-1-naphthalenesulfonate compete for binding to trp repressor. J Biol Chem 264:18309-13
Chou, W Y; Matthews, K S (1989) Mutation in hinge region of lactose repressor protein alters physical and functional properties. J Biol Chem 264:6171-6
Chakerian, A E; Matthews, K S (1988) Regulation of the lactose repressor. Int J Biochem 20:493-8