Methanotrophic bacteria utilize methane as their sole source of carbon and energy. The first step in their metabolic pathway is the oxidation of methane to methanol by methane monooxygenase (MMO) enzyme systems. As the only biological methane sink in an era of increased methane emissions, methanotrophs are a potential means to mitigate the deleterious effects of global warming on human health. In addition, methanotrophs can oxidize substrates besides methane, including halogenated hydrocarbons, and have been targeted for bioremediation applications. The predominant MMO in nature is particulate methane monooxygenase (pMMO), an oligomeric, integral membrane metalloenzyme. The long term goal of this project is to understand how pMMO and its homologs activate O2 for oxidation of methane and other substrates. Despite the recent identification of the pMMO active site, major questions surrounding pMMO structure and function remain to be addressed. The proposed research will focus on elucidating the atomic structure of the copper active site, the nature of the reactive species that oxidizes methane, the details of substrate, product, and reductant binding sites, and the role of the transmembrane domains. In addition, characterization of unique pMMO homologs will be pursued. The experimental approach involves spectroscopic, mechanistic, biochemical, and crystallographic characterization of native pMMO, recombinant pMMO, recombinant pMMO subunits and domains, and recombinant domains from related enzymes.

Public Health Relevance

Bacteria that consume methane gas play an important role in mitigating global warming, which has deleterious effects on human health. These bacteria also are useful for bioremediation of soil and water polluted with hydrocarbon carcinogens. This project will investigate the details of how these bacteria transform methane into methanol.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM070473-09
Application #
8502130
Study Section
Macromolecular Structure and Function E Study Section (MSFE)
Program Officer
Anderson, Vernon
Project Start
2004-05-01
Project End
2017-05-31
Budget Start
2013-06-01
Budget End
2014-05-31
Support Year
9
Fiscal Year
2013
Total Cost
$276,372
Indirect Cost
$76,372
Name
Northwestern University at Chicago
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
160079455
City
Evanston
State
IL
Country
United States
Zip Code
60201
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Sirajuddin, Sarah; Barupala, Dulmini; Helling, Stefan et al. (2014) Effects of zinc on particulate methane monooxygenase activity and structure. J Biol Chem 289:21782-94

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