# REGULATORY BIOLOGY OF PSEUDOMONAS TRYPTOPHAN SYNTHASE

> **NIH NIH R01** · UNIVERSITY OF IOWA · 1988 · $119,680

## Abstract

Pseudomonas aeruginosa tryptophan synthase originates from an unusual
two-gene biosynthetic operon regulated by substrate induction rather than
end product repression.  Expression of the adjacent structural genes for
the two enzyme subunits depends on a closely linked regulatory gene
producing a diffusible activator molecule augmenting expression in the
presence of effector molecules.  There is suggestive evidence that this
regulatory gene product may also repress expression somewhat in the absence
of the inducer.  The primary aim of this project is to clarify the
molecular events that are responsible for this regulation, which appears to
be unrelated to the regulation of tryptophan synthase in other bacteria and
to that of other enzymes of the tryptophan pathway in Pseudomonas.

A second aim is to elucidate the evolutionary changes that have affected
subunit interaction between the highly homologous Alpha2Beta2 tryptophan
synthase molecules of the fluorescent pseudomonads and the enteric
bacteria.  Conditions will be sought under which mutations improving
heterologous subunit cooperation can be selected.  A generous sampling of
such mutations should help to identify a subset of amino acids that:  a)
increase heterologous subunit affinity, or b) enhance cooperativity once
the subunits have associated.  When these changes are identified in the
Pseudomonas Beta chains the molecules containing them will be screened by
ELISA tests against a battery of monoclonal antibodies directed to the
native E. coli Beta2 subunit.

## Key facts

- **NIH application ID:** 3129848
- **Project number:** 5R01AI020279-06
- **Recipient organization:** UNIVERSITY OF IOWA
- **SAM.gov UEI:** Z1H9VJS8NG16
- **Principal Investigator:** IRVING P CRAWFORD
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1988
- **Award amount:** $119,680
- **Award type:** 5
- **Project period:** 1983-07-01 → 1989-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3129848

## Citation

> US National Institutes of Health, RePORTER application 3129848, REGULATORY BIOLOGY OF PSEUDOMONAS TRYPTOPHAN SYNTHASE (5R01AI020279-06). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3129848. Licensed CC0.

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