Structures of <i>Rhodopseudomonas palustris</i> RC-LH1 complexes with open or closed quinone channels.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33523887.
- Also identified by DOI 10.1126/sciadv.abe2631 and PMC identifier 7806223.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The reaction-center light-harvesting complex 1 (RC-LH1) is the core photosynthetic component in purple phototrophic bacteria. We present two cryo-electron microscopy structures of RC-LH1 complexes from <i>Rhodopseudomonas palustris</i> A 2.65-Å resolution structure of the RC-LH1<sub>14</sub>-W complex consists of an open 14-subunit LH1 ring surrounding the RC interrupted by protein-W, whereas the complex without protein-W at 2.80-Å resolution comprises an RC completely encircled by a closed, 16-subunit LH1 ring. Comparison of these structures provides insights into quinone dynamics within RC-LH1 complexes, including a previously unidentified conformational change upon quinone binding at the RC Q<sub>B</sub> site, and the locations of accessory quinone binding sites that aid their delivery to the RC. The structurally unique protein-W prevents LH1 ring closure, creating a channel for accelerated quinone/quinol exchange.