Conformation-specific crosslinking of mitochondrial complex I

Complex I is the only component of the eukaryotic respiratory chain of which no high-resolution structure is yet available. A notable feature of mitochondrial complex I is the so-called active/deactive conformational transition of the idle enzyme from the active (A) to the de-active, (D) form. Using an amine-and sulfhydryl-reactive crosslinker of 6.8 angstrom length (SPDP) we found that in the D-form of complex I the ND3 subunit crosslinked to the 39 kDa (NDUFA9) subunit. These proteins could not be crosslinked in the A-form. Most likely, both subunits are closely located in the critical junction region connecting the peripheral hydrophilic domain to the membrane arm of the enzyme where the entrance path for substrate ubiquinone is and where energy transduction takes place. Structured summary of protein interactions: ND3 and NDUFA9 physically interact by cross-linking study (View interaction) (C) 2013 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.