9etz | pdb_00009etz
III2IV respiratory supercomplex from Saccharomyces cerevisiae
Structural highlights
FunctionQCR1_YEAST Component of the ubiquinol-cytochrome c reductase complex (complex III or cytochrome b-c1 complex), which is part of the mitochondrial respiratory chain that generates an electrochemical potential coupled to ATP synthesis. The complex couples electron transfer from ubiquinol to cytochrome c. COR1 may mediate formation of the complex between cytochromes c and c1. Publication Abstract from PubMedRecent studies have established that cellular electrostatic interactions are more influential than assumed previously. Here, we use cryo-EM and perform steady-state kinetic studies to investigate electrostatic interactions between cytochrome (cyt.) c and the complex (C) III(2)-IV supercomplex from Saccharomyces cerevisiae at low salinity. The kinetic studies show a sharp transition with a Hill coefficient >/=2, which together with the cryo-EM data at 2.4 A resolution indicate multiple cyt. c molecules bound along the supercomplex surface. Negatively charged loops of CIII(2) subunits Qcr6 and Qcr9 become structured to interact with cyt. c. In addition, the higher resolution allows us to identify water molecules in proton pathways of CIV and, to the best of our knowledge, previously unresolved cardiolipin molecules. In conclusion, the lowered electrostatic screening renders engagement of multiple cyt. c molecules that are directed by electrostatically structured CIII(2) loops to conduct electron transfer between CIII(2) and CIV. Electron transfer in the respiratory chain at low salinity.,Lobez AP, Wu F, Di Trani JM, Rubinstein JL, Oliveberg M, Brzezinski P, Moe A Nat Commun. 2024 Sep 19;15(1):8241. doi: 10.1038/s41467-024-52475-3. PMID:39300056[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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