Document Detail


Charge-pairing interactions control the conformational setpoint and motions of the FMN domain in neuronal nitric oxide synthase.
MedLine Citation:
PMID:  23289611     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The NOS (nitric oxide synthase; EC 1.14.13.39) enzymes contain a C-terminal flavoprotein domain [NOSred (reductase domain of NOS)] that binds FAD and FMN, and an N-terminal oxygenase domain that binds haem. Evidence suggests that the FMN-binding domain undergoes large conformational motions to shuttle electrons between the NADPH/FAD-binding domain [FNR (ferredoxin NADP-reductase)] and the oxygenase domain. Previously we have shown 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 (neuronal NOSred). In the present study, we show that charge neutralization or reversal at each of these residues alters the setpoint [Keq(A)] of the NOSred conformational equilibrium to favour the open (FMN-deshielded) conformational state. Moreover, computer simulations of the kinetic traces of cytochrome c reduction by the mutants suggest that they have higher conformational transition rates (1.5-4-fold) and rates of interflavin electron transfer (1.5-2-fold) 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.
Authors:
Mohammad Mahfuzul Haque; Mekki Bayachou; Mohammed A Fadlalla; Deborah Durra; Dennis J Stuehr
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  The Biochemical journal     Volume:  450     ISSN:  1470-8728     ISO Abbreviation:  Biochem. J.     Publication Date:  2013 Mar 
Date Detail:
Created Date:  2013-02-28     Completed Date:  2013-04-17     Revised Date:  2014-03-26    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  England    
Other Details:
Languages:  eng     Pagination:  607-17     Citation Subset:  IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Binding Sites / genetics
Electron Transport
Flavin Mononucleotide / metabolism*
Humans
Kinetics
Models, Biological
Models, Molecular
Molecular Docking Simulation
Movement / physiology
Mutagenesis, Site-Directed
NADPH-Ferrihemoprotein Reductase / chemistry,  metabolism
Nitric Oxide Synthase Type I / chemistry*,  genetics,  metabolism*
Protein Binding / genetics
Protein Conformation
Protein Folding
Protein Interaction Domains and Motifs / genetics,  physiology*
Static Electricity
Grant Support
ID/Acronym/Agency:
GM51491/GM/NIGMS NIH HHS; HL58883/HL/NHLBI NIH HHS; P01 HL076491/HL/NHLBI NIH HHS; R01 GM051491/GM/NIGMS NIH HHS; R01 HL058883/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
7N464URE7E/Flavin Mononucleotide; EC 1.14.13.39/Nitric Oxide Synthase Type I; EC 1.6.2.4/NADPH-Ferrihemoprotein Reductase
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  A Royal Chartered College joins Chiropractic & Manual Therapies.
Next Document:  Radiorespirometric Assays For The Detection Of Biogenic Sulphides From Sulphate-Reducing Bacteria.