# Metalloenzymes and metal homeostasis

> **NIH NIH R35** · NORTHWESTERN UNIVERSITY · 2024 · $628,440

## Abstract

Project Summary
 This research program centers on the bioinorganic chemistry of methanotrophic bacteria, microbes that
convert methane, a potent greenhouse gas, to methanol in the first step of their metabolic pathway. As the
primary methane sink in nature, methanotrophs are promising tools to mitigate the deleterious effects of global
warming on human health, and may be deployed to generate fuels and chemicals from methane in an
environmentally-friendly fashion. Moreover, some methanotrophs produce copper-binding natural products that
are under investigation as therapeutics. The proposed projects take an integrated biochemical, biophysical,
structural, and genetic approach to understanding these processes on the molecular level.
 The first project addresses the structure and function of particulate methane monooxygenase (pMMO),
an integral membrane, copper-dependent enzyme that catalyzes the oxidation of methane to methanol. Despite
the availability of pMMO crystal structures and a range of spectroscopic data, the location and atomic details of
the copper active site remain unclear, and the sites of substrate, product, and reductant binding have not been
elucidated, all prerequisites for elucidating the chemical mechanism. The experimental approach involves
characterization of new pMMOs with highly divergent sequences, structural determination of pMMOs in a lipid
environment that maintains enzymatic activity, and genetic manipulation of native methanotrophs. The results
will lead to a comprehensive understanding of this critically important metalloenzyme and will further
understanding of homologs such as ammonia monooxygenase (AMO), another contributor to climate change.
 The second project focuses on methanobactins (Mbns), ribosomally produced, post-translationally
modified natural products secreted by methanotrophs to scavenge copper from the environment. The machinery
to biosynthesize and transport Mbns is encoded in Mbn operons, which are also present in a wide range of non-
methanotrophic bacteria, suggesting additional functions and unexplored diversity in structure. Mechanistic and
structural studies of the core biosynthetic enzyme complex, the iron-containing MbnBC heterodimer, along with
characterization of other biosynthetic proteins will be conducted. In addition, the involvement of other operon
proteins in release of copper from Mbn will be investigated using both biochemical and in vivo strategies. Taken
together, the results will provide new insights into natural products biosynthesis and will impact the use of these
molecules as therapeutics for Wilson disease and other disorders of copper metabolism.

## Key facts

- **NIH application ID:** 10809595
- **Project number:** 5R35GM118035-09
- **Recipient organization:** NORTHWESTERN UNIVERSITY
- **Principal Investigator:** AMY C. ROSENZWEIG
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $628,440
- **Award type:** 5
- **Project period:** 2016-04-01 → 2026-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10809595

## Citation

> US National Institutes of Health, RePORTER application 10809595, Metalloenzymes and metal homeostasis (5R35GM118035-09). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10809595. Licensed CC0.

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