# Investigating the role of Riboflavin and CidAB in Streptococcus mutans Anaerobic Metabolism

> **NIH NIH F31** · UNIVERSITY OF FLORIDA · 2020 · $38,140

## Abstract

Streptococcus mutans is a universal colonizer of the human oral cavity and is considered a primary causative
agent of dental caries. The organism has evolved to utilize a wide variety sugars and macromolecules in order
to generate energy which allows it to adapt to numerous environmental conditions. A common environmental
condition encountered by S. mutans is near or complete anaerobiosis: life with little or no oxygen. This condition
is often found in the oral cavity within complex, multi-species biofilms where nutrients are scarce and competition
between species is fierce. One important molecule that must be successfully gleaned is riboflavin, an essential
vitamin critical for co-factor generation as well as the activation of pyruvate formate lyase (PFL) by the PFL
activating enzyme (PFL-AE). Recent work has indicated that the primary mechanism for S. mutans riboflavin
acquisition lies proximal to a putative PFL-AE, which also is in close neighborhood association with genes
encoding the CidAB proteins. Expression of cidAB is highly upregulated during anaerobic growth, under
transcriptional control of CcpA, and this operon is important for S. mutans oxidative stress resistance.
Furthermore, the LrgAB proteins (homologous to CidAB) have been shown to act as pyruvate transporters in
Bacillus subtilis. Our collaborator's data indicates a similar role for LrgAB in S. mutans, and our lab's preliminary
data suggests that CidAB functions in the transport and/or metabolism of formate in this organism. This data,
combined with the predicted functions of genes within the chromosomal neighborhood of the cidAB operon,
suggests an important role for this genomic region in anaerobic metabolism. This project seeks to better
understand this aspect of S. mutans physiology by using a combination of genetic, metabolic, and proteomics
approaches to interrogate a) how this organism obtains and metabolizes riboflavin during anaerobic growth using
a novel molecular vitamin probe and b) how the CidAB proteins function in formate transport and/or metabolism
by analyzing metabolite profiles and physiological changes during anaerobic growth. These objectives will
advance our understanding as to how S. mutans is able to persist and compete within human oral cavity, and
how the organism is able to adapt its complex metabolism to different environmental conditions. Furthermore,
increased understanding of these processes will provide key insights into how S. mutans contributes to dental
caries, as well as novel targets for anti-microbial therapeutics.

## Key facts

- **NIH application ID:** 9991508
- **Project number:** 1F31DE029401-01A1
- **Recipient organization:** UNIVERSITY OF FLORIDA
- **Principal Investigator:** Matthew Turner
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $38,140
- **Award type:** 1
- **Project period:** 2020-05-15 → 2022-05-14

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9991508

## Citation

> US National Institutes of Health, RePORTER application 9991508, Investigating the role of Riboflavin and CidAB in Streptococcus mutans Anaerobic Metabolism (1F31DE029401-01A1). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9991508. Licensed CC0.

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