# Discovery and Characterization of Novel Halogenases from the Human Microbiome

> **NIH NIH R15** · UNIVERSITY OF TOLEDO · 2021 · $424,735

## Abstract

PROJECT SUMMARY/ABSTRACT
 Flavin-dependent halogenases (FDHs) are biosynthetic enzymes from bacteria and fungi
that catalyze regioselective C-X bond formation (X=Cl, Br, I) with various aromatic substrates.
Their regioselectivity and environmentally friendly reaction conditions make FDHs attractive
candidates for green synthesis of aryl halides to be used in transition metal catalyzed cross-
coupling reactions. The proposed project will expand our understanding of regioselective aryl
halide formation by FDHs through the identification and structural and enzymatic characterization
of novel members of this family of enzymes, expanding the FDH toolkit by adding new members
with different substrate and halide selectivities to the currently characterized enzymes.
 In Aim 1 of this project, we will fully characterize the extended substrate scope of AbeH
and BorH, two FDHs from soil bacteria metagenomes that we have shown can chlorinate and
brominate tryptophan to produce two different regioisomers. Aims 2 and 3 are based on our
hypothesis that FDHs are also produced by the bacteria of the human microbiome, where they
could potentially generate secondary metabolites that play a role in chemical communication
between bacteria and human cells. This hypothesis is supported by the fact that a simple
bioinformatic search of three sequence files from human microbiome metagenome shotgun
sequencing projects yielded five ORFs predicted to encode novel FDHs. Preliminary
investigations of the first of the five hypothetical FDH genes has verified that it encodes a protein
with the ability to halogenate indole. Aim 2 will involve the full characterization of the enzymatic
activity, substrate and halide scope, and crystal structures of these five putative microbiome
FDHs. Aim 3 will establish a training program in bioinformatics, enzymology, and structural
biology for undergraduate biochemistry majors, who will mine human microbiome metagenome
sequences for additional putative FDH genes, express and purify the gene products in E. coli,
and characterize their structures and activities.

## Key facts

- **NIH application ID:** 10360052
- **Project number:** 1R15GM144877-01
- **Recipient organization:** UNIVERSITY OF TOLEDO
- **Principal Investigator:** John J. Bellizzi
- **Activity code:** R15 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $424,735
- **Award type:** 1
- **Project period:** 2021-09-15 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10360052

## Citation

> US National Institutes of Health, RePORTER application 10360052, Discovery and Characterization of Novel Halogenases from the Human Microbiome (1R15GM144877-01). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10360052. Licensed CC0.

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