8aba
Complex III2 from Yarrowia lipolytica, ascorbate-reduced, int-position
Structural highlights
FunctionCYB_YARLI Component of the ubiquinol-cytochrome c reductase complex (complex III or cytochrome b-c1 complex) that is part of the mitochondrial respiratory chain. The b-c1 complex mediates electron transfer from ubiquinol to cytochrome c. Contributes to the generation of a proton gradient across the mitochondrial membrane that is then used for ATP synthesis.[UniProtKB:P00163] Publication Abstract from PubMedMovement of the Rieske domain of the iron-sulfur protein is essential for intramolecular electron transfer within complex III(2) (CIII(2)) of the respiratory chain as it bridges a gap in the cofactor chain towards the electron acceptor cytochrome c. We present cryo-EM structures of CIII(2) from Yarrowia lipolytica at resolutions up to 2.0 A under different conditions, with different redox states of the cofactors of the high-potential chain. All possible permutations of three primary positions were observed, indicating that the two halves of the dimeric complex act independently. Addition of the substrate analogue decylubiquinone to CIII(2) with a reduced high-potential chain increased the occupancy of the Q(o) site. The extent of Rieske domain interactions through hydrogen bonds to the cytochrome b and cytochrome c(1) subunits varied depending on the redox state and substrate. In the absence of quinols, the reduced Rieske domain interacted more closely with cytochrome b and cytochrome c(1) than in the oxidized state. Upon addition of the inhibitor antimycin A, the heterogeneity of the cd(1)-helix and ef-loop increased, which may be indicative of a long-range effect on the Rieske domain. Analysis of the conformational heterogeneity of the Rieske iron-sulfur protein in complex III(2) by cryo-EM.,Wieferig JP, Kuhlbrandt W IUCrJ. 2023 Jan 1;10(Pt 1):27-37. doi: 10.1107/S2052252522010570. PMID:36598500[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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