# REGULATORY BIOLOGY OF BACTERIAL TRYPTOPHAN SYNTHASE

> **NIH NIH R01** · UNIVERSITY OF IOWA · 1992 · $171,685

## Abstract

In the fluorescent pseudomonads an independent 3-gene cluster is
responsible for producing tryptophan synthase.  In addition to the 2-gene
operon encoding the enzyme's alpha and beta polypeptides, a divergently
transcribed activator gene (trpI) belonging to a new family of bacterial
regulators mediates induction of the enzyme by its substrate,
indoleglycerol phosphate.  We will examine the mechanism of this activation
through:  purification of the trpI gene product to homogeneity;
identification of its DNA-binding domain by evolutionary comparison,
directed mutagenesis and partial proteolysis; identification of its
chromosomal recognition site by evolutionary comparison, deletion analysis
and both spontaneous and directed mutagenesis; development of a
filter-binding assay to complement the available footprinting and gel
retardation assays; making fusions to place other genes (trpEGDC and xylE)
under trpI control.

In addition we will investigate the generality of the recently described
"tunnel" connecting the two active sites in the three-dimensional structure
of Salmonella typhimurium tryptophan synthase by examining its relationship
to an unusual class of "repairable" trpB mutants studied earlier.  We will:
clone and sequence most of the existing mutants (using the polymerase chain
reaction) to establish the nature and location of the amino acid
substitution; overproduce selected mutant proteins by use of a
high-expression vector; characterize the extent of "repairability" by the
trpA gene product and ammonium ions; correlate the enzymatic defect with
the ability of normal and borohydride-reduced beta 2 subunits to bind
indole.

## Key facts

- **NIH application ID:** 3129851
- **Project number:** 5R01AI020279-10
- **Recipient organization:** UNIVERSITY OF IOWA
- **SAM.gov UEI:** Z1H9VJS8NG16
- **Principal Investigator:** GARY N GUSSIN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1992
- **Award amount:** $171,685
- **Award type:** 5
- **Project period:** 1983-07-01 → 1994-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3129851

## Citation

> US National Institutes of Health, RePORTER application 3129851, REGULATORY BIOLOGY OF BACTERIAL TRYPTOPHAN SYNTHASE (5R01AI020279-10). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3129851. Licensed CC0.

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