Document Detail

Roles of subunit NuoK (ND4L) in the energy-transducing mechanism of Escherichia coli NDH-1 (NADH:quinone oxidoreductase).
MedLine Citation:
PMID:  23105119     Owner:  NLM     Status:  MEDLINE    
The bacterial H(+)-translocating NADH:quinone oxidoreductase (NDH-1) catalyzes electron transfer from NADH to quinone coupled with proton pumping across the cytoplasmic membrane. The NuoK subunit (counterpart of the mitochondrial ND4L subunit) is one of the seven hydrophobic subunits in the membrane domain and bears three transmembrane segments (TM1-3). Two glutamic residues located in the adjacent transmembrane helices of NuoK are important for the energy coupled activity of NDH-1. In particular, mutation of the highly conserved carboxyl residue ((K)Glu-36 in TM2) to Ala led to a complete loss of the NDH-1 activities. Mutation of the second conserved carboxyl residue ((K)Glu-72 in TM3) moderately reduced the activities. To clarify the contribution of NuoK to the mechanism of proton translocation, we relocated these two conserved residues. When we shifted (K)Glu-36 along TM2 to positions 32, 38, 39, and 40, the mutants largely retained energy transducing NDH-1 activities. According to the recent structural information, these positions are located in the vicinity of (K)Glu-36, present in the same helix phase, in an immediately before and after helix turn. In an earlier study, a double mutation of two arginine residues located in a short cytoplasmic loop between TM1 and TM2 (loop-1) showed a drastic effect on energy transducing activities. Therefore, the importance of this cytosolic loop of NuoK ((K)Arg-25, (K)Arg-26, and (K)Asn-27) for the energy transducing activities was extensively studied. The probable roles of subunit NuoK in the energy transducing mechanism of NDH-1 are discussed.
Jesus Torres-Bacete; Prem Kumar Sinha; Motoaki Sato; Gaurav Patki; Mou-Chieh Kao; Akemi Matsuno-Yagi; Takao Yagi
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2012-10-27
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  287     ISSN:  1083-351X     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-12-17     Completed Date:  2013-02-14     Revised Date:  2013-12-18    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  42763-72     Citation Subset:  IM    
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MeSH Terms
Amino Acid Sequence
Energy Metabolism*
Escherichia coli / enzymology*
Escherichia coli Proteins / metabolism*
Glutamic Acid / metabolism
Hydrogen-Ion Concentration
Membrane Proteins / metabolism*
Molecular Sequence Data
Mutant Proteins / chemistry,  metabolism
Mutation / genetics
NAD / metabolism
NADH Dehydrogenase / chemistry,  metabolism*
Native Polyacrylamide Gel Electrophoresis
Protein Structure, Secondary
Protein Subunits / chemistry,  metabolism*
Grant Support
Reg. No./Substance:
0/Escherichia coli Proteins; 0/Membrane Proteins; 0/Mutant Proteins; 0/Protein Subunits; 0/Protons; 0U46U6E8UK/NAD; 3KX376GY7L/Glutamic Acid; EC dehydrogenase subunit 4; EC protein, E coli; EC Dehydrogenase

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