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ToolsMartin, Elizabeth C., Bowie, Adam G. M., Wellfare Reid, Taylor, Hunter, C. Neil, Hitchcock, Andrew and Swainsbury, David J. K. (2024) Sulfoquinovosyl diacylglycerol is required for dimerisation of the Rhodobacter sphaeroides reaction centre-light harvesting 1 core complex. Biochemical Journal, 481 (13). pp. 823-838. ISSN 0264-6021
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Abstract
The reaction centre-light harvesting 1 (RC-LH1) core complex is indispensable for anoxygenic photosynthesis. In the purple bacterium Rhodobacter (Rba.) sphaeroides RC-LH1 is produced both as a monomer, in which 14 LH1 subunits form a C-shaped antenna around 1 RC, and as a dimer, where 28 LH1 subunits form an S-shaped antenna surrounding 2 RCs. Alongside the five RC and LH1 subunits, an additional polypeptide known as PufX provides an interface for dimerisation and also prevents LH1 ring closure, introducing a channel for quinone exchange that is essential for photoheterotrophic growth. Structures of Rba. sphaeroides RC-LH1 complexes revealed several new components; protein-Y, which helps to form the quinone channel; protein-Z, of unknown function and seemingly unique to dimers; and a tightly bound sulfoquinovosyl diacylglycerol (SQDG) lipid that interacts with two PufX arginine residues. This lipid lies at the dimer interface alongside weak density for a second molecule, previously proposed to be an ornithine lipid. In this work we have generated strains of Rba. sphaeroides lacking protein-Y, protein-Z, SQDG or ornithine lipids to assess the roles of these previously unknown components in the assembly and activity of RC-LH1. We show that whilst the removal of either protein-Y, protein-Z or ornithine lipids has only subtle effects, SQDG is essential for the formation of RC-LH1 dimers but its absence has no functional effect on the monomeric complex.
| Item Type: | Article |
|---|---|
| Additional Information: | Funding information: A.G.M.B. was supported by a University of Sheffield Faculty of Science PhD studentship awarded to C.N.H. C.N.H. acknowledges Synergy Award 854126 from the European Research Council, which partially supported E.C.M. and D.J.K.S. A.H. acknowledges a Royal Society University Research Fellowship (award no. URF\R1\191548), which partially supported E.C.M. D.J.K.S. acknowledges start-up funding from the University of East Anglia. |
| Faculty \ School: | Faculty of Science > School of Biological Sciences |
| Depositing User: | LivePure Connector |
| Date Deposited: | 08 Aug 2024 14:30 |
| Last Modified: | 12 Aug 2024 13:30 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/96185 |
| DOI: | 10.1042/BCJ20240125 |
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