| Conformational gating of electron transfer from the nitrogenase Fe protein to MoFe protein. | |
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MedLine Citation:
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PMID: 20429505 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The nitrogenase Fe protein contains a [4Fe-4S] cluster and delivers one electron at a time to the catalytic MoFe protein. During this electron delivery, the Fe protein in its [4Fe-4S](1+) reduced state (Fe(red)) binds two MgATP and forms a complex with the MoFe protein, with subsequent transfer of one electron to the MoFe protein in a reaction coupled to the hydrolysis of two ATP. Crystal structures with the nitrogenase complex in different nucleotide-bound states show major conformational changes which provide a structural underpinning to suggestions that intercomponent electron transfer (ET) is "gated" by conformational changes of the complex and/or of its component proteins. Although electron delivery is coupled to ATP hydrolysis, their connection is puzzling, for it appears that ET precedes both ATP hydrolysis and Pi release. We here test the gating hypothesis with studies of the intracomplex oxidation of Fe(red) by MoFe protein in the presence of a variety of solutes. Conformational control of this process (gating) is revealed by the finding that it responds to changes in osmotic pressure (but not viscosity), with no fewer than 80 waters being bound during the reaction. The absence of a solvent kinetic isotope effect further implies that ATP hydrolysis does not occur during the rate-limiting step of ET. |
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Authors:
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Karamatullah Danyal; Diana Mayweather; Dennis R Dean; Lance C Seefeldt; Brian M Hoffman |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural |
Journal Detail:
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Title: Journal of the American Chemical Society Volume: 132 ISSN: 1520-5126 ISO Abbreviation: J. Am. Chem. Soc. Publication Date: 2010 May |
Date Detail:
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Created Date: 2010-05-20 Completed Date: 2010-08-11 Revised Date: 2011-07-28 |
Medline Journal Info:
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Nlm Unique ID: 7503056 Medline TA: J Am Chem Soc Country: United States |
Other Details:
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Languages: eng Pagination: 6894-5 Citation Subset: IM |
Affiliation:
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Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adenosine Triphosphate
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metabolism Electron Transport Hydrolysis Kinetics Molybdoferredoxin / chemistry*, metabolism* Oxidoreductases / chemistry*, metabolism* Protein Conformation |
| Grant Support | |
ID/Acronym/Agency:
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GM59087/GM/NIGMS NIH HHS; HL63203/HL/NHLBI NIH HHS; R01 GM059087-10/GM/NIGMS NIH HHS; R01 HL013531-38/HL/NHLBI NIH HHS; R01 HL063203-13/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Molybdoferredoxin; 56-65-5/Adenosine Triphosphate; EC 1.-/Oxidoreductases; EC 1.18.6.1/nitrogenase reductase |
| Comments/Corrections | |
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