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E. coli NADH quinone oxidoreductase hydrophilic arm
Structural highlights
FunctionNUOB_ECOLI NDH-1 shuttles electrons from NADH, via FMN and iron-sulfur (Fe-S) centers, to quinones in the respiratory chain. The immediate electron acceptor for the enzyme in this species is ubiquinone. Couples the redox reaction to proton translocation (for every two electrons transferred, four hydrogen ions are translocated across the cytoplasmic membrane), and thus conserves the redox energy in a proton gradient. Publication Abstract from PubMedRespiratory complex I drives proton translocation across energy-transducing membranes by NADH oxidation coupled with (ubi)quinone reduction. In humans, its dysfunction is associated with neurodegenerative diseases. The Escherichia coli complex represents the structural minimal form of an energy-converting NADH:ubiquinone oxidoreductase. Here, we report the structure of the peripheral arm of the E. coli complex I consisting of six subunits, the FMN cofactor, and nine iron-sulfur clusters at 2.7 A resolution obtained by cryo electron microscopy. While the cofactors are in equivalent positions as in the complex from other species, individual subunits are adapted to the absence of supernumerary proteins to guarantee structural stability. The catalytically important subunits NuoC and D are fused resulting in a specific architecture of functional importance. Striking features of the E. coli complex are scrutinized by mutagenesis and biochemical characterization of the variants. Moreover, the arrangement of the subunits sheds light on the unknown assembly of the complex. Structure of the peripheral arm of a minimalistic respiratory complex I.,Schimpf J, Oppermann S, Gerasimova T, Santos Seica AF, Hellwig P, Grishkovskaya I, Wohlwend D, Haselbach D, Friedrich T Structure. 2022 Jan 6;30(1):80-94.e4. doi: 10.1016/j.str.2021.09.005. Epub 2021 , Sep 24. PMID:34562374[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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