# Sulfide Oxidation and Signaling

> **NIH NIH R35** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2020 · $390,000

## Abstract

The tripartite interaction between dietary fiber and protein intake, microbial fermentation and
host cell metabolism, is on display in the colon where epithelial cells are routinely exposed to
high concentrations of the respiratory poison, hydrogen sulfide (H2S). H2S is also beneficent; it
is used for signaling via persulfidation, a posttranslational modification, and is a substrate for the
electron transfer chain, generating ATP. Thiosulfate is the primary product of H2S oxidation in
colon and its synthesis involves three mitochondrial enzymes: sulfide quinone oxidoreductase
(SQR), a persulfide dioxygenase (PDO), and a sulfurtransferase. We have found that the apical
localization of all three enzymes in colonic crypts is influenced by the presence or absence of
microbiota and that these enzymes are significantly overexpressed in colon cancer. We now
seek to expand from our initial focus on the enzymology of human sulfide oxidation enzymes to
the interconnection between the oxidation pathways for H2S and butyrate, which is the preferred
fuel for colonocytes and is furnished by microbial metabolism. We posit that prioritization of H2S
over butyrate oxidation (to avert poisoning), is achieved via coenzyme A persulfide (CoASSH)
produced by SQR and oxidized by PDO. CoASSH inhibits butyryl-CoA dehydrogenase
(ACADS), explaining why native ACADS has long been purified as a “green” enzyme due to an
inhibitory charge transfer complex between CoASSH and the flavin cofactor. To test this
hypothesis, we will determine the kinetics of CoASSH synthesis and its inhibition of ACADS in
vitro and of butyrate oxidation in cells with normal or ablated SQR or PDO expression. We will
also determine the structures of human SQR and PDO (with a tightly bound inhibitor) to inform
our kinetic and cellular studies and will assess the competition between SQR and complexes I
and II for a limited coenzyme Q pool. Using a proteomic method, we have identified >1800
persulfide targets and we will investigate the role of H2S signaling in modulating metabolism in
nonmalignant and malignant colon epithelial cells. For this, we will use radiolabel tracing and
metabolomics analyses to assess the influence of sulfide on central carbon, nucleotide and lipid
metabolism, evaluate the role of a sulfurtransferase in catalytic persulfidation of protein targets,
and assess the influence of gut microbiota and diet on host sulfide metabolism. The impact of
our broad and rigorous attack on the challenging study of sulfide-mediated signaling and
metabolic modulation, supported by strong ongoing collaborations (with a physician scientist,
cancer cell biologists, a microbiologist and physical chemists), will be to provide fundamentally
important biological insights at the relatively unexplored host-microbiome interface.

## Key facts

- **NIH application ID:** 9841947
- **Project number:** 5R35GM130183-02
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** RUMA V BANERJEE
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $390,000
- **Award type:** 5
- **Project period:** 2019-01-01 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9841947

## Citation

> US National Institutes of Health, RePORTER application 9841947, Sulfide Oxidation and Signaling (5R35GM130183-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9841947. Licensed CC0.

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