7c9r

Publication Abstract from PubMed

The light-harvesting-reaction center complex (LH1-RC) from the purple phototrophic bacterium Thiorhodovibrio strain 970 exhibits an LH1 absorption maximum at 960 nm, the most red-shifted absorption for any bacteriochlorophyll (BChl) a-containing species. Here we present a cryo-EM structure of the strain 970 LH1-RC complex at 2.82 A resolution. The LH1 forms a closed ring structure composed of sixteen pairs of the alphabeta-polypeptides. Sixteen Ca ions are present in the LH1 C-terminal domain and are coordinated by residues from the alphabeta-polypeptides that are hydrogen-bonded to BChl a. The Ca(2+)-facilitated hydrogen-bonding network forms the structural basis of the unusual LH1 redshift. The structure also revealed the arrangement of multiple forms of alpha- and beta-polypeptides in an individual LH1 ring. Such organization indicates a mechanism of interplay between the expression and assembly of the LH1 complex that is regulated through interactions with the RC subunits inside.

Cryo-EM structure of a Ca(2+)-bound photosynthetic LH1-RC complex containing multiple alphabeta-polypeptides.,Tani K, Kanno R, Makino Y, Hall M, Takenouchi M, Imanishi M, Yu LJ, Overmann J, Madigan MT, Kimura Y, Mizoguchi A, Humbel BM, Wang-Otomo ZY Nat Commun. 2020 Oct 2;11(1):4955. doi: 10.1038/s41467-020-18748-3. PMID:33009385^[1]

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