Pseudomonas aeruginosa tryptophan synthase is an unusual biosynthetic operon regulated by substrate induction rather than end product repression. Preliminary genetic studies indicate that expression of the structural genes for the two enzyme subunits depends on a closely linked regulatory gene with a diffusible product that activates transcription in the presence of effector molecules. There is suggestive evidence that this regulatory gene product also represses expression somewhat in the absence of the inducer. This project aims to confirm and quantify this activation-induction model by in vitro experiments and to determine the DNA sequence of the structural and regulatory elements. It will also investigate the nature of constitutive mutants in the system. Just as the fluorescent pseudomonads have evolved a novel regulatory system for tryptophan synthase, so have the enzymes structural genes evolved so that they cannot interact productively with subunits from other bacteria. Mutational analysis will be used to identify the specific regions of the molecule involved in this discrimination. This should identify a subset of residues likely not previously recognized as crtical to enzyme function.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI020279-03
Application #
3129846
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1983-07-01
Project End
1986-06-30
Budget Start
1985-07-01
Budget End
1986-06-30
Support Year
3
Fiscal Year
1985
Total Cost
Indirect Cost
Name
University of Iowa
Department
Type
Schools of Medicine
DUNS #
041294109
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Subbramanian, Ramu A; Moriya, Chikaya; Martin, Kristi L et al. (2004) Engineered T-cell receptor tetramers bind MHC-peptide complexes with high affinity. Nat Biotechnol 22:1429-34
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Chang, M; Crawford, I P (1991) In vitro determination of the effect of indoleglycerol phosphate on the interaction of purified TrpI protein with its DNA-binding sites. J Bacteriol 173:1590-7
Crawford, I P; Han, C Y; Silverman, M (1991) Sequence and features of the tryptophan operon of Vibrio parahemolyticus. DNA Seq 1:189-96
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Bae, Y M; Crawford, I P (1990) The Rhizobium meliloti trpE(G) gene is regulated by attenuation, and its product, anthranilate synthase, is regulated by feedback inhibition. J Bacteriol 172:3318-27
Chang, M; Crawford, I P (1990) The roles of indoleglycerol phosphate and the TrpI protein in the expression of trpBA from Pseudomonas aeruginosa. Nucleic Acids Res 18:979-88
Crawford, I P (1989) Evolution of a biosynthetic pathway: the tryptophan paradigm. Annu Rev Microbiol 43:567-600
Chang, M; Hadero, A; Crawford, I P (1989) Sequence of the Pseudomonas aeruginosa trpI activator gene and relatedness of trpI to other procaryotic regulatory genes. J Bacteriol 171:172-83

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