# Noncompetitive inhibition of CYP121 dimers from Mycobacterium tuberculosis

> **NIH NIH R21** · STATE UNIVERSITY OF NEW YORK AT BUFFALO · 2024 · $241,375

## Abstract

Project Summary and Abstract
Tuberculosis (TB) continues as a global pandemic and remains the leading cause of death by infection
worldwide. The rise of multi-drug resistant forms of Mycobacterium tuberculosis (Mtb) highlights the need to
develop novel anti-TB therapeutics. A promising drug target is the essential enzyme Cytochrome P450 21A1
(CYP121) of Mtb, which catalyzes a phenol-coupling reaction to convert dicyclotyrosine (cYY) into the cyclical
compound mycocyclosin. Since attempts to delete the CYP121 gene result in non-viable bacteria, various drug
design efforts have focused on the development of competitive active site inhibitors of the enzyme. CYP inhibition
typically involves the use of a nitrogen heterocycle that forms a coordinate covalent bond with the heme iron.
However, given the high degree of structural homology within the CYP superfamily, theoretical competitive
inhibition of CYP121 carries significant risks due to the potential for non-specific inhibition of drug-metabolizing
CYPs like CYP3A4. Patients undergoing treatment for TB are subjected to a rigorous regiment of medications
like rifampicin and isoniazid, among others, some of which are already competitive inhibitors of drug metabolizing
CYPs. In the current proposal, the development of non-competitive inhibition of CYP121 is proposed. The
enzyme displays the unusual feature of relying on a distal-to-distal homodimer interface for its function. Notably,
this particular interface does not occur in mammalian CYPs. Specific Aim 1 centers on the use of a cleavable
fusion of the CYP121 homodimer in combination with enzyme kinetics, 19F-NMR, and loss of function mutations
to test the hypothesis of monomer-to-monomer cross-talk across the dimer interface. In Aim 2, virtual drug
screening will be used to develop potential pharmacophores located near the dimer interface. The short-term
goal of this work is to lay the foundation for a robust investigation of candidate small-molecule binding sites on
the protein surface that inhibit without binding the active site; the long-term goal is to develop novel classes of
non-competitive CYP121 inhibitors that avoid the potential for drug-drug interactions in patients being treated for
TB.

## Key facts

- **NIH application ID:** 10865896
- **Project number:** 1R21AI182823-01
- **Recipient organization:** STATE UNIVERSITY OF NEW YORK AT BUFFALO
- **Principal Investigator:** David Fernando Estrada
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $241,375
- **Award type:** 1
- **Project period:** 2024-05-20 → 2026-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10865896

## Citation

> US National Institutes of Health, RePORTER application 10865896, Noncompetitive inhibition of CYP121 dimers from Mycobacterium tuberculosis (1R21AI182823-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10865896. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*