1932

Abstract

Abstract

Crystal structures and their implications for function are described for the energy transducing hetero-oligomeric dimeric cytochrome complex of oxygenic photosynthesis from the thermophilic cyanobacterium, , and the green alga, The complex has a cytochrome core and a central quinone exchange cavity, defined by the two monomers that are very similar to those in the respiratory cytochrome complex. The pathway of quinol/quinone (Q/QH) transfer emphasizes the labyrinthine internal structure of the complex, including an 11×12 Å portal through which Q/QH, containing a 45-carbon isoprenoid chain, must pass. Three prosthetic groups are present in the complex that are not found in the related complex: a chlorophyll (Chl) , a β-carotene, and a structurally unique covalently bound heme that does not possess amino acid side chains as axial ligands. It is hypothesized that this heme, exposed to the cavity and a neighboring plastoquinone and close to the positive surface potential of the complex, can function in cyclic electron transport via anionic ferredoxin.

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/content/journals/10.1146/annurev.biochem.75.103004.142756
2006-07-07
2024-04-14
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/content/journals/10.1146/annurev.biochem.75.103004.142756
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  • Article Type: Review Article
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