Olsen, J. D., Adams, P. G., Jackson, P. J. orcid.org/0000-0001-9671-2472 et al. (3 more authors) (2014) Aberrant Assembly Complexes of the Reaction Center Light-harvesting 1 PufX (RC-LH1-PufX) Core Complex of Rhodobacter sphaeroides Imaged by Atomic Force Microscopy. Journal of Biological Chemistry, 289 (43). pp. 29927-29936. ISSN 0021-9258
Abstract
In the purple phototrophic bacterium Rhodobacter sphaeroides, many protein complexes congregate within the membrane to form operational photosynthetic units consisting of arrays of light-harvesting LH2 complexes and monomeric and dimeric reaction center (RC)-light-harvesting 1 (LH1)-PufX “core” complexes. Each half of a dimer complex consists of a RC surrounded by 14 LH1 αβ subunits, with two bacteriochlorophylls (Bchls) sandwiched between each αβ pair of transmembrane helices. We used atomic force microscopy (AFM) to investigate the assembly of single molecules of the RC-LH1-PufX complex using membranes prepared from LH2-minus mutants. When the RC and PufX components were also absent, AFM revealed a series of LH1 variants where the repeating α1β1(Bchl)2 units had formed rings of variable size, ellipses, and spirals and also arcs that could be assembly products. The spiral complexes occur when the LH1 ring has failed to close, and short arcs are suggestive of prematurely terminated LH1 complex assembly. In the absence of RCs, we occasionally observed captive proteins enclosed by the LH1 ring. When production of LH1 units was restricted by lowering the relative levels of the cognate pufBA transcript, we imaged a mixture of complete RC-LH1 core complexes, empty LH1 rings, and isolated RCs, leading us to conclude that once a RC associates with the first α1β1(Bchl)2 subunit, cooperative associations between subsequent subunits and the RC tend to drive LH1 ring assembly to completion.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | Free via Creative Commons: CC-BY license. © 2014 The Author(s). This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | Atomic Force Microscopy (AFM); Bacteria; Membrane Biogenesis; Membrane Protein; Photosynthesis; Light Harvesting; Reaction Center |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Chemical and Biological Engineering (Sheffield) The University of Sheffield > Faculty of Science (Sheffield) > School of Biosciences (Sheffield) > Department of Molecular Biology and Biotechnology (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 13 Mar 2017 14:28 |
Last Modified: | 13 Mar 2017 14:28 |
Published Version: | http://dx.doi.org/10.1074/jbc.M114.596585 |
Status: | Published |
Publisher: | American Society for Biochemistry and Molecular Biology |
Refereed: | Yes |
Identification Number: | 10.1074/jbc.M114.596585 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:113514 |