Identification of protein W, the elusive sixth subunit of the Rhodopseudomonas palustris reaction center-light harvesting 1 core complex

Jackson, Philip J., Hitchcock, Andrew, Swainsbury, David J.K., Qian, Pu, Martin, Elizabeth C., Farmer, David A., Dickman, Mark J., Canniffe, Daniel P. and Hunter, C. Neil (2018) Identification of protein W, the elusive sixth subunit of the Rhodopseudomonas palustris reaction center-light harvesting 1 core complex. Biochimica et Biophysica Acta - Bioenergetics, 1859 (2). pp. 119-128. ISSN 0005-2728

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Abstract

The X-ray crystal structure of the Rhodopseudomonas (Rps.) palustris reaction center-light harvesting 1 (RC-LH1) core complex revealed the presence of a sixth protein component, variably referred to in the literature as helix W, subunit W or protein W. The position of this protein prevents closure of the LH1 ring, possibly to allow diffusion of ubiquinone/ubiquinol between the RC and the cytochrome bc1 complex in analogous fashion to the well-studied PufX protein from Rhodobacter sphaeroides. The identity and function of helix W have remained unknown for over 13 years; here we use a combination of biochemistry, mass spectrometry, molecular genetics and electron microscopy to identify this protein as RPA4402 in Rps. palustris CGA009. Protein W shares key conserved sequence features with PufX homologs, and although a deletion mutant was able to grow under photosynthetic conditions with no discernible phenotype, we show that a tagged version of protein W pulls down the RC-LH1 complex. Protein W is not encoded in the photosynthesis gene cluster and our data indicate that only approximately 10% of wild-type Rps. palustris core complexes contain this non-essential subunit; functional and evolutionary consequences of this observation are discussed. The ability to purify uniform RC-LH1 and RC-LH1-protein W preparations will also be beneficial for future structural studies of these bacterial core complexes.

Item Type: Article
Additional Information: Funding Information: This work was supported by the European Research Council (Advanced Award 338895 ); the Biotechnology and Biological Sciences Research Council ( BBSRC ) UK (Award numbers BB/M000265/1 , BB/M011151/1 and BB/M012166/1 ); the Photosynthetic Antenna Research Center ( PARC ), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science , Office of Basic Energy Sciences (Award number DE-SC0001035 ); and the European Commission (Marie Skłodowska-Curie Global Fellowship 660652 ). Publisher Copyright: © 2017
Uncontrolled Keywords: helix w,photosynthesis,pufx,reaction center-light harvesting 1 (rc-lh1) core complex,rhodopseudomonas palustris,rpa4402,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: 24 Sep 2022 07:04
URI: https://ueaeprints.uea.ac.uk/id/eprint/87363
DOI: 10.1016/j.bbabio.2017.11.001

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