| Charge Pairing Interactions Control the Conformational Setpoint and Motions of the FMN Domain in Neuronal Nitric Oxide Synthase. | |
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MedLine Citation:
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PMID: 23289611 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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The Nitric Oxide Synthases (NOS; EC 1.14.13.39) contain a C-terminal flavoprotein domain (NOSred) that binds FAD and FMN and an N-terminal oxygenase domain that binds heme. Evidence suggests that the FMN-binding domain undergoes large conformational motions to shuttle electrons between the NADPH/FAD-binding domain (FNR) and the oxygenase domain. previously we showed that three residues on the FMN domain (Glu762, Glu816 and Glu819) that make charge-pairing interactions with the FNR help to slow electron flux through nNOSred. In this study, we show that charge neutralization or reversal at each of these residues alters the setpoint (KeqA) of the NOSred conformational equilibrium to favor of the open (FMN-deshielded) conformational state. Moreover, computer simulations of the kinetic traces of cytochrome c reduction by the mutants suggest that they have relatively larger effects on the conformational transition rates (from 1.5 to 4x faster) and the rate of interflavin electron transfer (from 1.5 to 2x faster) relative to wild type nNOSred. We conclude that the three charge-pairing residues on the FMN domain govern electron flux through nNOSred by stabilizing its closed (FMN-shielded) conformational state and by retarding the rate of conformational switching between its open and closed conformations. |
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Authors:
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Mohammad Mahfuzul Haque; Mekki Bayachou; Mohammed A Fadlalla; Deborah Durra; Dennis J Stuehr |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2013-1-7 |
Journal Detail:
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Title: The Biochemical journal Volume: - ISSN: 1470-8728 ISO Abbreviation: Biochem. J. Publication Date: 2013 Jan |
Date Detail:
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Created Date: 2013-1-7 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 2984726R Medline TA: Biochem J Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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