# MECHANISM OF CARBOHYDRATES TRANSPORT IN BACTERIA

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA, SAN DIEGO · 1991 · $261,107

## Abstract

The phosphoenolpyruvate:sugar phosphotransferase system (PTS) is a complex
enzyme system which in Salmonella typhimurium and Escherichia coli
catalyzes the concomitant transmembrane transport and phosphorylation of
its sugar substrates.  It also regulates the utilization of a variety of
carbon sources not taken up via the PTS-catalyzed group translocation
mechanism.  Studies in our laboratory have provided information regarding
the mechanisms by which the PTS functions in catalysis and regulation of
carbon metabolism.  We have cloned and sequenced many of the gene encoding
PTS proteins and proteins which regulate their expression, and have
conducted extensive molecular genetic and biochemical analyses to define
their mechanisms of action.  These studies have allowed us to define the
allosteric mechanism by which PTS-mediated protein phosphorylation
regulates the activities of non-PTS carbohydrate permeases, catabolic
enzymes and adenylate cyclase.  Recently, our studies have shown that the
fructose (fru) regulon is exceptionally complex and that the fru repressor
(FruR) together with other fructose-specific proteins regulates
transcription of hundreds of genes encoding enzymes involved in Salmonella
pathogenesis and central pathways of carbon metabolism (glycolysis, the
Krebs cycle, the glyoxylate shunt, gluconeogenesis, and electron transfer).
The purpose of the proposed research is to extend our understanding of the
fru regulon, the fructose-specific PTS proteins and their involvement in
sugar transport and transcriptional regulation.  Employing Salmonella
typhimurium, a combined biochemical and molecular genetic approach will be
taken as follows:

1.  We will sequence the fruR gene and overproduce and purify         FruR
for physicochemical, DNA binding and in vitro         transcription
studies.  Other proteins believed to be         involved in regulation will
similarly be prepared.  Target        genes to be studied include those of
the fru regulon which        are negatively regulated by FruR as well as
those encoding        enzymes of central metabolic pathways which are
positively        regulated by FruR.  The possible involvement of the
enzymes       of the fructose PTS and protein phosphorylation will be
  tested.
2.  We will characterize the various components of the fru         regulon
including cryptic genes encoding duplicate copies of      PTS energy
coupling proteins and permeases.  We will also         characterize the
Enzyme IIIfru-MR-FPr and the Enzyme IIfru        proteins in order to
define the structure-function         relationships of their various
domains.  X-ray diffraction        studies (to be conducted
collaboratively) will complement the     molecular genetic and biochemical
studies proposed.

## Key facts

- **NIH application ID:** 3125670
- **Project number:** 2R01AI014176-14
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN DIEGO
- **SAM.gov UEI:** UYTTZT6G9DT1
- **Principal Investigator:** MILTON H. SAIER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1991
- **Award amount:** $261,107
- **Award type:** 2
- **Project period:** 1977-09-01 → 1996-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3125670

## Citation

> US National Institutes of Health, RePORTER application 3125670, MECHANISM OF CARBOHYDRATES TRANSPORT IN BACTERIA (2R01AI014176-14). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3125670. Licensed CC0.

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