# Regulation of a gene associated with c-di-GMP production and biofilm formation in Vibrio cholerae

> **NIH NIH R03** · LOUISIANA STATE UNIV A&M COL BATON ROUGE · 2021 · $69,438

## Abstract

PROJECT SUMMARY/ABSTRACT
Cholera is a diarrheal disease characterized by life-threatening dehydration. It is caused by serotypes of the
Gram-negative bacterium Vibrio cholerae, which produce cholera toxin. One of the strains linked to endemic
cholera outbreaks is the O1 serotype El Tor. V. cholerae El Tor forms biofilms, which are protective
communities in which the bacteria are shielded from environmental stress. The second messenger bis-(3'-5')-
cyclic-diguanylate monophosphate (c-di-GMP) is key to the transition between motile and sessile (biofilm)
lifestyles, with high levels of c-di-GMP associated with biofilm formation. Synthesis of c-di-GMP requires
diguanylate cyclase enzymes. One such diguanylate cyclase, which is encoded by VCA0956 and named
CdgF, has been linked to biofilm formation and to formation of the hyper-infective bacterial aggregates that
form during late infection and are released from the intestinal tract in preparation for bacterial re-entry into the
aqueous environment. Mechanisms by which cdgF expression is regulated are unknown. In this project, we
will investigate the hypotheses that cdgF expression is controlled by the divergently encoded MarR family
transcription factor that we named DgcR, and that DgcR responds to the ligand c-di-GMP, thus creating a
positive feed-back loop that sustains c-di-GMP synthesis. We also propose that initial expression of cdgF
occurs when DgcR is oxidized, an event that attenuates its ability to bind the cdgF promoter and repress
transcription. DNA and ligand binding by DgcR will be determined in vitro by DNase I footprinting and by
biophysical analyses of DgcR in absence and presence of ligand. Control of cdgF promoter activity in vivo will
be addressed using cdgF promoter-reporter constructs in E. coli also expressing inducible dgcR, and the
ability of c-di-GMP or oxidant to de-repress gene expression will be determined. In vitro transcription assays
will be implemented to complement the in vivo assays. Completion of the proposed experiments is expected
to delineate a novel feed-back system in which c-di-GMP sustains its own synthesis, and it is expected to
define a direct link between oxidative stress and c-di-GMP accumulation. Knowing the mechanisms by which
the clinically relevant CdgF enzyme is produced is important for a better understanding of V. cholerae El Tor
pathogenicity, and it will open prospects for interfering with this regulation and hence prevent formation of the
biofilm communities against which conventional antimicrobial agents are ineffective.

## Key facts

- **NIH application ID:** 10198717
- **Project number:** 5R03AI153556-02
- **Recipient organization:** LOUISIANA STATE UNIV A&M COL BATON ROUGE
- **Principal Investigator:** ANNE GROVE
- **Activity code:** R03 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $69,438
- **Award type:** 5
- **Project period:** 2020-06-19 → 2023-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10198717

## Citation

> US National Institutes of Health, RePORTER application 10198717, Regulation of a gene associated with c-di-GMP production and biofilm formation in Vibrio cholerae (5R03AI153556-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10198717. Licensed CC0.

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