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Publication Abstract from PubMed

The reaction center-light-harvesting complex 1 (RC-LH1) plays an essential role in the primary reactions of bacterial photosynthesis. Here, we present high-resolution structures of native monomeric and dimeric RC-LH1 supercomplexes from Rhodobacter (Rba.) blasticus using cryo-electron microscopy. The RC-LH1 monomer is composed of an RC encircled by an open LH1 ring comprising 15 alphabeta heterodimers and a PufX transmembrane polypeptide. In the RC-LH1 dimer, two crossing PufX polypeptides mediate dimerization. Unlike Rhodabacter sphaeroides counterpart, Rba. blasticus RC-LH1 dimer has a less bent conformation, lacks the PufY subunit near the LH1 opening, and includes two extra LH1 alphabeta subunits, forming a more enclosed S-shaped LH1 ring. Spectroscopic assays reveal that these unique structural features are accompanied by changes in the kinetics of quinone/quinol trafficking between RC-LH1 and cytochrome bc(1). Our findings reveal the assembly principles and structural variability of photosynthetic RC-LH1 supercomplexes, highlighting diverse strategies used by phototrophic bacteria to optimize light-harvesting and electron transfer in competitive environments.

Architectures of photosynthetic RC-LH1 supercomplexes from Rhodobacter blasticus.,Wang P, Christianson BM, Ugurlar D, Mao R, Zhang Y, Liu ZK, Zhang YY, Gardner AM, Gao J, Zhang YZ, Liu LN Sci Adv. 2024 Oct 11;10(41):eadp6678. doi: 10.1126/sciadv.adp6678. Epub 2024 Oct , 9. PMID:39383221^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.