title: Structure of the cytochrome b6f complex of oxygenic photosynthesis: tuning the cavity.
abstract: The cytochrome b6f complex provides the electronic connection between the photosystem I and photosystem II reaction centers of oxygenic photosynthesis and generates a transmembrane electrochemical proton gradient for adenosine triphosphate synthesis. A 3.0 angstrom crystal structure of the dimeric b6f complex from the thermophilic cyanobacterium Mastigocladus laminosus reveals a large quinone exchange cavity, stabilized by lipid, in which plastoquinone, a quinone-analog inhibitor, and a novel heme are bound. The core of the b6f complex is similar to the analogous respiratory cytochrome bc1 complex, but the domain arrangement outside the core and the complement of prosthetic groups are strikingly different. The motion of the Rieske iron-sulfur protein extrinsic domain, essential for electron transfer, must also be different in the b6f complex.
authors.affiliation: Department of Biological Sciences, 915 West State Street, Purdue University, West Lafayette, IN 47907-2054, USA.
authors.forename: Genji
authors.initials: G
authors.lastname: Kurisu
authors.forename: Huamin
authors.initials: H
authors.lastname: Zhang
authors.forename: Janet L
authors.initials: JL
authors.lastname: Smith
authors.forename: William A
authors.initials: WA
authors.lastname: Cramer
mesh_terms: D002462:Cell Membrane / Q000737:chemistry; D003460:Crystallization; D018360:Crystallography, X-Ray; D000458:Cyanobacteria / Q000737:chemistry* / Q000378:metabolism; D045346:Cytochrome b6f Complex / Q000737:chemistry* / Q000378:metabolism; D045348:Cytochromes f / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D004579:Electron Transport; D014450:Electron Transport Complex III / Q000737:chemistry / Q000378:metabolism; D006418:Heme / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism; D008051:Lipid Bilayers; D008958:Models, Molecular; D010788:Photosynthesis; D010971:Plastoquinone / Q000737:chemistry / Q000378:metabolism; D011090:Polyenes / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry; D011522:Protons
chemical_list: D007506:Iron-Sulfur Proteins; D008051:Lipid Bilayers; D011090:Polyenes; D021122:Protein Subunits; D011522:Protons; C037989:Rieske iron-sulfur protein; D006418:Heme; D045346:Cytochrome b6f Complex; D045348:Cytochromes f; C041573:stigmatellin; D014450:Electron Transport Complex III; D010971:Plastoquinone