Single particle analysis confirms distal location of subunits NuoL and NuoM in Escherichia coli complex I.
Respiratory complex I catalyses the transfer of electrons from NADH to quinone coupled to the translocation of protons across the membrane. The mechanism of coupling and the structure of the complete enzyme are not known. The membrane domain of the complex contains three similar antiporter-like subunits NuoL/M/N, probably involved in proton pumping. We have previously shown that subunits NuoL/M can be removed from the rest of the complex, suggesting their location at the distal end of the membrane domain. Here, using electron microscopy and single particle analysis, we show that subunits NuoL and M jointly occupy a distal half of the membrane domain, separated by about 10nm from the interface with the peripheral arm. This indicates that coupling mechanism of complex I is likely to involve long range conformational changes.
Baranova
Ekaterina A
EA
Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, UK.
Morgan
David J
DJ
Sazanov
Leonid A
LA
D042967:Electron Transport Complex I / Q000737:chemistry*; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000648:ultrastructure; D009245:NADH Dehydrogenase / Q000737:chemistry* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry*
D029968:Escherichia coli Proteins; D021122:Protein Subunits; D009245:NADH Dehydrogenase; C479743:NuoL protein, E coli; C476247:NuoM protein, E coli; D042967:Electron Transport Complex I