Methanotrophic bacteria utilize methane as their sole carbon and energy source. The first step in their metabolic pathway is the oxidation of methane to methanol by methane monooxygenase (MMO) enzyme systems. All but one genus of methanotrophs produce a membrane-bound, copper-containing enzyme called particulate methane monooxygenase (pMMO). Although pMMO is the predominant methane oxidation catalyst in nature, it has proved difficult to isolate, and most investigators have instead opted to study soluble methane monooxygenase (sMMO), a diiron carboxylate-bridged enzyme that is more tractable, but less universal, than pMMO. The structure and mechanism of pMMO and the homologous enzyme ammonia monooxygenase (AMO) remain one of the major unsolved problems in bioinorganic chemistry. Understanding how pMMO activates O2 for oxidation of methane and other hydrocarbons is the long term goal of this research program. Despite the availability of a crystal structure and extensive spectroscopic data, key questions regarding the metal content and active site identity remain unanswered. These issues are of fundamental importance to bioinorganic copper chemistry and have implications for the use of methanotrophs in bioremediation. In addition, methanotrophs play a key role in the global carbon cycle and could help mitigate the deleterious effects of global warming on human health. The proposed research involves purification and characterization of pMMO and AMO from multiple organisms. State-of-the-art crystallization techniques for membrane proteins will be applied to these enzymes. In addition, expression systems will be developed to enable site-directed mutagenesis experiments. Finally, in vitro enzyme activity will be optimized and mechanistic studies initiated.

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 #
5R01GM070473-06
Application #
7847626
Study Section
Special Emphasis Panel (ZRG1-BCMB-B (02))
Program Officer
Anderson, Vernon
Project Start
2004-05-01
Project End
2013-05-31
Budget Start
2010-06-01
Budget End
2011-05-31
Support Year
6
Fiscal Year
2010
Total Cost
$273,128
Indirect Cost
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
Ross, Matthew O; Rosenzweig, Amy C (2017) A tale of two methane monooxygenases. J Biol Inorg Chem 22:307-319
Blanchette, Craig D; Knipe, Jennifer M; Stolaroff, Joshuah K et al. (2016) Printable enzyme-embedded materials for methane to methanol conversion. Nat Commun 7:11900
Lawton, Thomas J; Rosenzweig, Amy C (2016) Biocatalysts for methane conversion: big progress on breaking a small substrate. Curr Opin Chem Biol 35:142-149
Lawton, Thomas J; Kenney, Grace E; Hurley, Joseph D et al. (2016) The CopC Family: Structural and Bioinformatic Insights into a Diverse Group of Periplasmic Copper Binding Proteins. Biochemistry 55:2278-90
Kenney, Grace E; Goering, Anthony W; Ross, Matthew O et al. (2016) Characterization of Methanobactin from Methylosinus sp. LW4. J Am Chem Soc 138:11124-7
Lawton, Thomas J; Rosenzweig, Amy C (2016) Methane-Oxidizing Enzymes: An Upstream Problem in Biological Gas-to-Liquids Conversion. J Am Chem Soc 138:9327-40
Trana, Ethan N; Nocek, Judith M; Woude, Jon Vander et al. (2016) Charge-Disproportionation Symmetry Breaking Creates a Heterodimeric Myoglobin Complex with Enhanced Affinity and Rapid Intracomplex Electron Transfer. J Am Chem Soc 138:12615-28
Rosenzweig, Amy C (2015) Biochemistry: Breaking methane. Nature 518:309-10
Sirajuddin, Sarah; Rosenzweig, Amy C (2015) Enzymatic oxidation of methane. Biochemistry 54:2283-94
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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