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ToolsSwainsbury, David J.K., Hawkings, Frederick R., Martin, Elizabeth C., Musiał, Sabina, Salisbury, Jack H., Jackson, Philip J., Farmer, David A., Johnson, Matthew P., Siebert, C. Alistair, Hitchcock, Andrew and Hunter, C. Neil (2023) Cryo-EM structure of the four-subunit Rhodobacter sphaeroides cytochrome bc1 complex in styrene maleic acid nanodiscs. Proceedings of the National Academy of Sciences of the United States of America, 120 (12). ISSN 0027-8424
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Abstract
Cytochrome bc1 complexes are ubiquinol:cytochrome c oxidoreductases, and as such, they are centrally important components of respiratory and photosynthetic electron transfer chains in many species of bacteria and in mitochondria. The minimal complex has three catalytic components, which are cytochrome b, cytochrome c1, and the Rieske iron–sulfur subunit, but the function of mitochondrial cytochrome bc1 complexes is modified by up to eight supernumerary subunits. The cytochrome bc1 complex from the purple phototrophic bacterium Rhodobacter sphaeroides has a single supernumerary subunit called subunit IV, which is absent from current structures of the complex. In this work we use the styrene–maleic acid copolymer to purify the R. sphaeroides cytochrome bc1 complex in native lipid nanodiscs, which retains the labile subunit IV, annular lipids, and natively bound quinones. The catalytic activity of the four-subunit cytochrome bc1 complex is threefold higher than that of the complex lacking subunit IV. To understand the role of subunit IV, we determined the structure of the four-subunit complex at 2.9 Å using single particle cryogenic electron microscopy. The structure shows the position of the transmembrane domain of subunit IV, which lies across the transmembrane helices of the Rieske and cytochrome c1 subunits. We observe a quinone at the Qo quinone-binding site and show that occupancy of this site is linked to conformational changes in the Rieske head domain during catalysis. Twelve lipids were structurally resolved, making contacts with the Rieske and cytochrome b subunits, with some spanning both of the two monomers that make up the dimeric complex.
| Item Type: | Article |
|---|---|
| Additional Information: | Data, Materials, and Software Availability: The structures and EM maps have been deposited in the protein data bank (PDB) and electron microscopy data bank (EMDB) with the following accession IDs: Consensus refinement with the Rieske domain in the b-position: PDB ID: 8ASI (95), EMDB: EMD-15616 (96). Focussed class with the Riseke domains in the b- and c- positions: PDB ID: 8ASJ (97), EMDB: EMD-15617 (98). The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository (http://proteomecentral.proteomexchange.org) with the dataset identifier PXD039340 (99). All study data are included in the article and/or SI Appendix. Funding Information: D.J.K.S, E.C.M, and C.N.H were supported by Biotechnology and Biological Sciences Research Council (BBSRC) UK, award number BB/M000265/1, and European Research Council Synergy Award 854126. D.J.K.S was also supported by the University of East Anglia new investigator start-up funding. F.R.H. was supported by a Diamond Light Source PhD studentship (number STU0355) jointly funded by the University of Sheffield. A.H. is supported by a Royal Society University Research Fellowship, which also funds a PhD studentship to J.H.S. (award number URF\R1\191548). D.A.F and C.A.S. acknowledge Diamond Light Source for access and support of the cryo-EM facilities at the UK's national Electron Bio-Imaging Centre at Diamond Light Source under proposal nr29785. M.P.J. acknowledges support from the BBSRC (award number BB/V006630/1) and the Leverhulme Trust (Grant RPG-2019-045). |
| Uncontrolled Keywords: | cytochrome bc,evolution,photosynthesis,quinone,rhodobacter sphaeroides,general ,/dk/atira/pure/subjectarea/asjc/1000 |
| Faculty \ School: | Faculty of Science > School of Biological Sciences |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 01 Nov 2024 12:31 |
| Last Modified: | 12 Nov 2024 13:30 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/97424 |
| DOI: | 10.1073/pnas.2217922120 |
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