|3rko, resolution 3.00Å ()|
|Sites:||, , , , , , , , , , , , , , , , , , and|
Crystal structure of the membrane domain of respiratory complex I from E. coli at 3.0 angstrom resolution
Complex I is the first and largest enzyme of the respiratory chain, coupling electron transfer between NADH and ubiquinone to the translocation of four protons across the membrane. It has a central role in cellular energy production and has been implicated in many human neurodegenerative diseases. The L-shaped enzyme consists of hydrophilic and membrane domains. Previously, we determined the structure of the hydrophilic domain. Here we report the crystal structure of the Esherichia coli complex I membrane domain at 3.0 A resolution. It includes six subunits, NuoL, NuoM, NuoN, NuoA, NuoJ and NuoK, with 55 transmembrane helices. The fold of the homologous antiporter-like subunits L, M and N is novel, with two inverted structural repeats of five transmembrane helices arranged, unusually, face-to-back. Each repeat includes a discontinuous transmembrane helix and forms half of a channel across the membrane. A network of conserved polar residues connects the two half-channels, completing the proton translocation pathway. Unexpectedly, lysines rather than carboxylate residues act as the main elements of the proton pump in these subunits. The fourth probable proton-translocation channel is at the interface of subunits N, K, J and A. The structure indicates that proton translocation in complex I, uniquely, involves coordinated conformational changes in six symmetrical structural elements.
Structure of the membrane domain of respiratory complex I., Efremov RG, Sazanov LA, Nature. 2011 Aug 7. doi: 10.1038/nature10330. PMID:21822288
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
About this Structure
3rko is a 12 chain structure with sequence from Escherichia coli. The December 2011 RCSB PDB Molecule of the Month feature on Complex I by David Goodsell is 10.2210/rcsb_pdb/mom_2011_12. Full crystallographic information is available from OCA.