An atypical haem in the cytochrome b6f complex

Photosystems I and II (PSI and II) are reaction centres that capture light energy in order to drive oxygenic photosynthesis; however, they can only do so by interacting with the multisubunit cytochrome b 6 f complex. This complex receives electrons from PSII and passes them to PSI, pumping protons a...

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Bibliographic Details
Published in:Nature (London) 2003-11, Vol.426 (6965), p.413-418
Main Authors: Stroebel, David, Choquet, Yves, Popot, Jean-Luc, Picot, Daniel
Format: Article
Language:English
Subjects:
Amino acids
Analytical, structural and metabolic biochemistry
Biological and medical sciences
Cell biochemistry
Cell physiology
Chlamydomonas reinhardtii
Cytochrome
cytochrome b6f
Fundamental and applied biological sciences. Psychology
Hemoproteins
Humanities and Social Sciences
Metalloproteins
multidisciplinary
Photosynthesis
Plant physiology and development
Proteins
Science
Science (multidisciplinary)
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Summary:Photosystems I and II (PSI and II) are reaction centres that capture light energy in order to drive oxygenic photosynthesis; however, they can only do so by interacting with the multisubunit cytochrome b 6 f complex. This complex receives electrons from PSII and passes them to PSI, pumping protons across the membrane and powering the Q-cycle. Unlike the mitochondrial and bacterial homologue cytochrome bc 1 , cytochrome b 6 f can switch to a cyclic mode of electron transfer around PSI using an unknown pathway. Here we present the X-ray structure at 3.1 Å of cytochrome b 6 f from the alga Chlamydomonas reinhardtii . The structure bears similarities to cytochrome bc 1 but also exhibits some unique features, such as binding chlorophyll, β-carotene and an unexpected haem sharing a quinone site. This haem is atypical as it is covalently bound by one thioether linkage and has no axial amino acid ligand. This haem may be the missing link in oxygenic photosynthesis.
ISSN:0028-0836
1476-4687
DOI:10.1038/nature02155