Primary Citation of Related Structures:   7C9R
PubMed Abstract: 
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 Å resolution. The LH1 forms a closed ring structure composed of sixteen pairs of the αβ-polypeptides. Sixteen Ca ions are present in the LH1 C-terminal domain and are coordinated by residues from the αβ-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 α- and β-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.
Organizational Affiliation: 
Graduate School of Medicine, Mie University, Tsu, 514-8507, Japan. ktani@doc.medic.mie-u.ac.jp.
Imaging Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1, Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan.
Faculty of Science, Ibaraki University, Mito, 310-8512, Japan.
Department of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe, 657-8501, Japan.
Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
Leibniz-Institute DSMZ-German Collection of Microorganisms and Cell Cultures, 38124, Braunschweig, Germany.
Faculty of Life Science, Institute of Microbiology, Braunschweig University of Technology, Braunschweig, Germany.
Department of Microbiology, Southern Illinois University, Carbondale, IL, 62901, USA.
Graduate School of Medicine, Mie University, Tsu, 514-8507, Japan.
Faculty of Science, Ibaraki University, Mito, 310-8512, Japan. wang@ml.ibaraki.ac.jp.