8b64
From Proteopedia
Cryo-EM structure of RC-LH1-PufX photosynthetic core complex from Rba. capsulatus
Structural highlights
FunctionLHA1_RHOCA Antenna complexes are light-harvesting systems, which transfer the excitation energy to the reaction centers. Publication Abstract from PubMedIn purple photosynthetic bacteria, the photochemical reaction center (RC) and light-harvesting complex 1 (LH1) assemble to form monomeric or dimeric RC-LH1 membrane complexes, essential for bacterial photosynthesis. Here, we report a 2.59-A resolution cryoelectron microscopy (cryo-EM) structure of the RC-LH1 supercomplex from Rhodobacter capsulatus. We show that Rba. capsulatus RC-LH1 complexes are exclusively monomers in which the RC is surrounded by a 15-subunit LH1 ring. Incorporation of a transmembrane polypeptide PufX leads to a large opening within the LH1 ring. Each LH1 subunit associates two carotenoids and two bacteriochlorophylls, which is similar to Rba. sphaeroides RC-LH1 but more than one carotenoid per LH1 in Rba. veldkampii RC-LH1 monomer. Collectively, the unique Rba. capsulatus RC-LH1-PufX represents an intermediate structure between Rba. sphaeroides and Rba. veldkampii RC-LH1-PufX. Comparison of PufX from the three Rhodobacter species indicates the important residues involved in dimerization of RC-LH1. Cryo-EM structure of a monomeric RC-LH1-PufX supercomplex with high-carotenoid content from Rhodobacter capsulatus.,Bracun L, Yamagata A, Christianson BM, Shirouzu M, Liu LN Structure. 2023 Mar 2;31(3):318-328.e3. doi: 10.1016/j.str.2023.01.006. Epub 2023 , Feb 3. PMID:36738736[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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