The Cytochrome b6 Complex of Oxygenic Photosynthesis | Semantic Scholar (2024)

Important advances include: the high-resolution structures of Cyt b 6 f and Cyt bc 1 complexes; evidence for domain movement of the Rieske iron-sulfur protein subunit during catalysis; discovery of a previously undetected c-type heme required for transmembrane electron flow and activity of the plastoquinone-reductase site of Cyr 6 f complexes.

The enhanced rate of superoxide production in the b6f complex is physiologically significant as the chloroplast-generated reactive oxygen species (ROS) functions in the regulation of excess excitation energy, is a source of oxidative damage inflicted during photosynthetic reactions, and is a major source of ROS in plant cells.

A detailed and comprehensive picture on the heterocyst demands for Fe, Cu, Mo, Ni, Mn, V, and Zn as cofactors for metalloproteins is provided and highlights the importance of such metalliproteins for the biology of cyanobacterial heterocysts.

This study supplies a new perspective for comprehending the phylogeny and evolution of Ferula and indicates that Talassia transiliensis and Soranthus meyeri were nested in the Ferula genus, and thus they should be transferred into theFerula genus.

This is the first study that conducted phylogenetic and evolutionary analyses on the genus Allium combined with the plastome and morphological and cytological data and detected a well-supported phylogenetic relationship of Allium.

This study uncovered a new species relationship in section Daghestanica and suggested that the selective pressure has played an important role in Allium adaptation and evolution, which will facilitate the further understanding of evolution and adaptation of species in the genus Allium.

The dimeric b6f complex from the thermophilic cyanobacterium Mastigocladus laminosus reveals a large quinone exchange cavity, stabilized by lipid, in which plastoquinone, a quin one-analog inhibitor, and a novel heme are bound.

The X-ray structure of cytochrome b6f from the alga Chlamydomonas reinhardtii is presented and it is shown that this haem is atypical as it is covalently bound by one thioether linkage and has no axial amino acid ligand, which may be the missing link in oxygenic photosynthesis.

The likely presence of cyclic electron transport in the b6 f complex, and of heme cn in the firmicute bc complex suggests the concept that hemes bn‐cn define a branch point in bc complexes that can support electron transport pathways that differ in detail from the Q cycle supported by the bc1 complex.

The structure and position of heme x suggest that it could function in ferredoxin-dependent cyclic electron transport as well as being an intermediate in a quinone cycle mechanism for electron and proton transfer.

It is proposed that in the cytochrome b(6)f complex, the protection is at least partly realized through special arrangement of the local protein structure, which shortens the singlet excited state lifetime of the Chl a by a factor of 20-25 and thus significantly reduces the formation of theChl a triplet state.

X-ray crystal structures of the cytochrome bc1 complex from chicken, cow and rabbit in both the presence and absence of inhibitors of quinone oxidation, reveal two different locations for the extrinsic domain of one component of the enzyme, an iron–sulphur protein.

...

...