# Regulation of H2S Biogenesis

> **NIH NIH R01** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2020 · $390,000

## Abstract

Abstract
Hydrogen sulfide (H2S) is toxic at high concentrations but beneficial at low, eliciting profound effects on
physiological functions ranging from cardioprotection to hippocampal long-term potentiation, to protection
against intestinal inflammation. Its toxicity is averted by the robust activity of a mitochondrial sulfide oxidation
pathway, which feeds into the electron transfer chain, linking H2S to energy metabolism. H2S is the product of
three enzymes in the sulfur network of which two, cystathionine β-synthase (CBS) and γ-cystathionase (CSE),
reside in the cytoplasmic transsulfuration pathway while the third, mercaptopyruvate sulfurtransferase (MST),
is involved in cysteine catabolism and is primarily mitochondrial in location. Studies in our laboratory have
provided detailed insights into the kinetic and chemical mechanisms of the human enzymes revealing a
suprising laxity in substrate and reaction specificity particularly for CBS and CSE. Together, the
transsulfuration enzymes catalyze at least eight H2S generating reactions in addition to the two canonical
cysteine producing reactions, raising the obvious question of how substrate and reaction choices are regulated
in a cellular milieu. In the next cycle, we propose to elucidate fundamental mechanisms of regulation of H2S
synthesis in normal and disease states by addressing the following specific aims: (i) Elucidate allosteric
regulation in CBS, which we have recently discovered uses a unique mechanism via its heme cofactor, to
regulate the choice of substrate for CSE, the next enzyme in the pathway. For this, we will exploit an enigmatic
set of pathogenic CBS mutations that retain normal activity but exhibit faulty allosteric regulation that is exerted
over 50 Å of protein terrain. (ii) Elucidate regulation of H2S synthesis by CSE in the context of angiogenesis in
which NO· and CO play a role, and which we can now connect to CSE via the NO· and CO-sensistive heme-
regulated switch in CBS. We will also develop CSE inhibitors by optimizing lead compounds that show
specificity towards CSE, the major H2S producer in the peripheral system. (iii) We will elucidate the role of MST
in proliferation and cellular bioenergetics, building on our unpublished studies, which reveal significant up-
regulation of MST in colon cancer. We will also assess the impact of MST on H2S signaling using a newly
developed, sensitive, and specific persulfide tagging method for proteomic analysis. The impact of our
proposed studies will be both fundamental (i.e. elucidating mechanims of allosteric regulation at the level of
individual enzymes and in the pathway), and medical (i.e. understanding the biochemical basis of failure of
disease-causing CBS mutations, developing CSE inhibitors with therapeutic potential and identifying changes
in the persulfide proteome in colon cancer associated with metabolic reprogramming).

## Key facts

- **NIH application ID:** 9944657
- **Project number:** 5R01HL058984-21
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** RUMA V BANERJEE
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $390,000
- **Award type:** 5
- **Project period:** 1997-08-01 → 2022-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9944657

## Citation

> US National Institutes of Health, RePORTER application 9944657, Regulation of H2S Biogenesis (5R01HL058984-21). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9944657. Licensed CC0.

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