Probing the local lipid environment of the Rhodobacter sphaeroides cytochrome bc1 and Synechocystis sp. PCC 6803 cytochrome b6f complexes with styrene maleic acid

Swainsbury, David J.K., Proctor, Matthew S., Hitchcock, Andrew, Cartron, Michaël L., Qian, Pu, Martin, Elizabeth C., Jackson, Philip J., Madsen, Jeppe, Armes, Steven P. and Hunter, C. Neil (2018) Probing the local lipid environment of the Rhodobacter sphaeroides cytochrome bc1 and Synechocystis sp. PCC 6803 cytochrome b6f complexes with styrene maleic acid. Biochimica Et Biophysica Acta-Bioenergetics, 1859 (3). pp. 215-225. ISSN 0005-2728

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Intracytoplasmic vesicles (chromatophores) in the photosynthetic bacterium Rhodobacter sphaeroides represent a minimal structural and functional unit for absorbing photons and utilising their energy for the generation of ATP. The cytochrome bc1 complex (cytbc1) is one of the four major components of the chromatophore alongside the reaction centre-light harvesting 1-PufX core complex (RC-LH1-PufX), the light-harvesting 2 complex (LH2), and ATP synthase. Although the membrane organisation of these complexes is known, their local lipid environments have not been investigated. Here we utilise poly(styrene-alt-maleic acid) (SMA) co-polymers as a tool to simultaneously determine the local lipid environments of the RC-LH1-PufX, LH2 and cytbc1 complexes. SMA has previously been reported to effectively solubilise complexes in lipid-rich membrane regions whilst leaving lipid-poor ordered protein arrays intact. Here we show that SMA solubilises cytbc1 complexes with an efficiency of nearly 70%, whereas solubilisation of RC-LH1-PufX and LH2 was only 10% and 22% respectively. This high susceptibility of cytbc1 to SMA solubilisation is consistent with this complex residing in a locally lipid-rich region. SMA solubilised cytbc1 complexes retain their native dimeric structure and co-purify with 56 ± 6 phospholipids from the chromatophore membrane. We extended this approach to the model cyanobacterium Synechocystis sp. PCC 6803, and show that the cytochrome b6f complex (cytb6f) and Photosystem II (PSII) complexes are susceptible to SMA solubilisation, suggesting they also reside in lipid-rich environments. Thus, lipid-rich membrane regions could be a general requirement for cytbc1/cytb6f complexes, providing a favourable local solvent to promote rapid quinol/quinone binding and release at the Q0 and Qi sites.

Item Type: Article
Additional Information: Funding Information: DJKS, AH, ECM and CNH gratefully acknowledge financial support from the Biotechnology and Biological Sciences Research Council (BBSRC UK), award number BB/M000265/1 . CNH was also supported by Advanced Award 338895 from the European Research Council . PQ and PJJ were supported by European Research Council (Advanced Award 338895 ). MLC was supported by Engineering and Physical sciences Research Council (EPSRC grant EP/I012060/1 ). MSP was supported by a University of Sheffield doctoral studentship funded by the BBSRC. Publisher Copyright: © 2018 The Authors
Uncontrolled Keywords: cytochrome bf,cytochrome bc,quinone pool,rba. sphaeroides,sma,synechocystis,biophysics,biochemistry,cell biology ,/dk/atira/pure/subjectarea/asjc/1300/1304
Faculty \ School: Faculty of Science > School of Biological Sciences
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Depositing User: LivePure Connector
Date Deposited: 17 Aug 2022 12:31
Last Modified: 14 Jul 2024 01:26
DOI: 10.1016/j.bbabio.2017.12.005

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