scholarly journals Cryo-EM structure of the Rhodospirillum rubrum RC-LH1 complex at 2.5 Å

2021 ◽  
Author(s):  
Pu Qian ◽  
Tristan Ian Croll ◽  
David JK Swainsbury ◽  
Pablo Castro-Hartmann ◽  
Nigel W Moriarty ◽  
...  
Keyword(s):  
Rhodospirillum Rubrum ◽  
Bacterial Photosynthesis ◽  
General Mechanism ◽  
Reaction Centre ◽  
Circular Array ◽  
Bc1 Complex ◽  
Cytochrome Bc1 Complex ◽  
The Core ◽  
Cryo Electron Microscopy ◽  
Preferential Binding

The reaction centre light-harvesting 1 (RC-LH1) complex is the core functional component of bacterial photosynthesis. We determined the cryo-electron microscopy (cryo-EM) structure of the RC-LH1 complex from Rhodospirillum rubrum at 2.5 Å resolution, which reveals a unique monomeric bacteriochlorophyll with a phospholipid ligand in the gap between RC and LH1 complexes. The LH1 complex comprises a circular array of 16 αβ-polypeptide subunits that completely surrounds the RC, with a preferential binding site for a quinone, designated QP, on the inner face of the encircling LH1 complex. Quinols, initially generated at the RC QB site, are proposed to transiently occupy the QP site prior to traversing the LH1 barrier and diffusing to the cytochrome bc1 complex. Thus, the QP site, which is analogous to other such sites in recent cryo-EM structures of RC-LH1 complexes, likely reflects a general mechanism for exporting quinols from the RC-LH1 complex.

The Rhodospirillum rubrum cytochrome bc1 complex: redox properties, inhibitor sensitivity and proton pumping

1991 ◽  
Vol 1058 (2) ◽  
pp. 269-279 ◽  
Author(s):  
Saadettin Güner ◽  
Dan E. Robertson ◽  
Linda Yu ◽  
Zhi-hau Qiu ◽  
Chang-An Yu ◽  
...  
Keyword(s):  
Rhodospirillum Rubrum ◽  
Proton Pumping ◽  
Redox Properties ◽  
Cytochrome Bc1 ◽  
Bc1 Complex ◽  
Cytochrome Bc1 Complex

Binding site on Rhodospirillum rubrum cytochrome c2 for the Rhodospirillum rubrum cytochrome bc1 complex

Biochemistry ◽  
1987 ◽  
Vol 26 (24) ◽  
pp. 7688-7693 ◽  
Author(s):  
Hans Rudolf Bosshard ◽  
R. Max Wynn ◽  
David B. Knaff
Keyword(s):  
Binding Site ◽  
Rhodospirillum Rubrum ◽  
Cytochrome Bc1 ◽  
Bc1 Complex ◽  
Cytochrome Bc1 Complex ◽  
Cytochrome C2

scholarly journals Cryo-EM structure of the Rhodobacter sphaeroides RC-LH1 core monomer complex at 2.5 Å

2021 ◽  
Author(s):  
Pu Qian ◽  
David JK Swainsbury ◽  
Tristan Ian Croll ◽  
Jack H Salisbury ◽  
Elizabeth C Martin ◽  
...  
Keyword(s):  
Rhodobacter Sphaeroides ◽  
Light Harvesting ◽  
Ring Structure ◽  
Bacterial Photosynthesis ◽  
Reaction Centre ◽  
Cytochrome Bc1 Complex ◽  
Protein Subunit ◽  
Proton Transfers ◽  
Monomeric Complex ◽  
Essential Components

Reaction centre light-harvesting 1 (RC-LH1) complexes are the essential components of bacterial photosynthesis. The membrane-intrinsic LH1 complex absorbs light and the energy migrates to an enclosed RC where a succession of electron and proton transfers conserves the energy as a quinol, which is exported to the cytochrome bc1 complex. In some RC-LH1 variants quinols can diffuse through small pores in a fully circular, 16-subunit LH1 ring, while in others missing LH1 subunits create a gap for quinol export. We used cryogenic electron microscopy to obtain a 2.5 Å resolution structure of one such RC-LH1, a monomeric complex from Rhodobacter sphaeroides. The structure shows that the RC is partly enclosed by a 14-subunit LH1 ring in which each αβ heterodimer binds two bacteriochlorophylls and, unusually for currently reported complexes, two carotenoids rather than one. Although the extra carotenoids confer an advantage in terms of photoprotection and light harvesting, they could block small pores in the LH1 ring and impede passage of quinones, necessitating a mechanism to create a dedicated quinone channel. The structure shows that two transmembrane proteins play a part in stabilizing an open ring structure; one of these components, the PufX polypeptide, is augmented by a hitherto undescribed protein subunit we designate as protein-Y, which lies against the transmembrane regions of the thirteenth and fourteenth LH1α polypeptides. Protein-Y prevents LH1 subunits 11-14 adjacent to the RC QB site from bending inwards towards the RC and, with PufX preventing complete encirclement of the RC, this pair of polypeptides ensures unhindered

scholarly journals Structures of Rhodopseudomonas palustris RC-LH1 complexes with open or closed quinone channels

2021 ◽  
Vol 7 (3) ◽  
pp. eabe2631
Author(s):  
David J. K. Swainsbury ◽  
Pu Qian ◽  
Philip J. Jackson ◽  
Kaitlyn M. Faries ◽  
Dariusz M. Niedzwiedzki ◽  
...  
Keyword(s):  
Binding Sites ◽  
Rhodopseudomonas Palustris ◽  
Ring Closure ◽  
Light Harvesting Complex ◽  
The Core ◽  
Quinone Binding ◽  
Cryo Electron Microscopy ◽  
Unique Protein ◽  
Center Light ◽  
Resolution Structure

The reaction-center light-harvesting complex 1 (RC-LH1) is the core photosynthetic component in purple phototrophic bacteria. We present two cryo–electron microscopy structures of RC-LH1 complexes from Rhodopseudomonas palustris. A 2.65-Å resolution structure of the RC-LH114-W complex consists of an open 14-subunit LH1 ring surrounding the RC interrupted by protein-W, whereas the complex without protein-W at 2.80-Å resolution comprises an RC completely encircled by a closed, 16-subunit LH1 ring. Comparison of these structures provides insights into quinone dynamics within RC-LH1 complexes, including a previously unidentified conformational change upon quinone binding at the RC QB site, and the locations of accessory quinone binding sites that aid their delivery to the RC. The structurally unique protein-W prevents LH1 ring closure, creating a channel for accelerated quinone/quinol exchange.

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