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Publication Abstract from PubMed

Rhodobacter sphaeroides is a model organism in bacterial photosynthesis, and its light-harvesting-reaction center (LH1-RC) complex contains both dimeric and monomeric forms. Here we present cryo-EM structures of the native LH1-RC dimer and an LH1-RC monomer lacking protein-U (DeltaU). The native dimer reveals several asymmetric features including the arrangement of its two monomeric components, the structural integrity of protein-U, the overall organization of LH1, and rigidities of the proteins and pigments. PufX plays a critical role in connecting the two monomers in a dimer, with one PufX interacting at its N-terminus with another PufX and an LH1 beta-polypeptide in the other monomer. One protein-U was only partially resolved in the dimeric structure, signaling different degrees of disorder in the two monomers. The DeltaU LH1-RC monomer was half-moon-shaped and contained 11 alpha- and 10 beta-polypeptides, indicating a critical role for protein-U in controlling the number of alphabeta-subunits required for dimer assembly and stabilization. These features are discussed in relation to membrane topology and an assembly model proposed for the native dimeric complex.

Asymmetric structure of the native Rhodobacter sphaeroides dimeric LH1-RC complex.,Tani K, Kanno R, Kikuchi R, Kawamura S, Nagashima KVP, Hall M, Takahashi A, Yu LJ, Kimura Y, Madigan MT, Mizoguchi A, Humbel BM, Wang-Otomo ZY Nat Commun. 2022 Apr 7;13(1):1904. doi: 10.1038/s41467-022-29453-8. PMID:35393413^[1]

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