ArticleThe Journal of biological chemistry2009
Is the redox state of the ci heme of the cytochrome b6f complex dependent on the occupation and structure of the Qi site and vice versa?
Article in The Journal of biological chemistry, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 14 papers.
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Who cites it
14 citing papers in PubMed, 29 citations in OpenAlex.
- Article
- Plant responses to gaseous pollutants, biochemical and transcriptomic insights.Frontiers in plant science · 2026Review
- The stromal side of the cytochrome b6f complex regulates state transitions.The Plant cell · 2024Article
- Cryo-EM structures of the Synechocystis sp. PCC 6803 cytochrome b6f complex with and without the regulatory PetP subunit.The Biochemical journal · 2022Article
- Protein Engineering of Electron Transfer Components from ElectroactiveAntioxidants (Basel, Switzerland) · 2021Review
- Catalytic Reactions and Energy Conservation in the CytochromeChemical reviews · 2021Review
- Emergence of cytochrome bc complexes in the context of photosynthesis.Physiologia plantarum · 2017Article
- Cytochrome b 6 f function and localization, phosphorylation state of thylakoid membrane proteins and consequences on cyclic electron flow.Photosynthesis research · 2016Review
- The involvement of hydrogen-producing and ATP-dependent NADPH-consuming pathways in setting the redox poise in the chloroplast of Chlamydomonas reinhardtii in anoxia.The Journal of biological chemistry · 2015Article
- Photosynthesis-related quantities for education and modeling.Photosynthesis research · 2013Review
- Heme ligand identification and redox properties of the cytochrome c synthetase, CcmF.Biochemistry · 2011Article
- Photosynthetic growth despite a broken Q-cycle.Nature communications · 2011Article
- Heliobacterial Rieske/cytb complex.Photosynthesis research · 2010Article
- Evolution of cytochrome bc complexes: from membrane-anchored dehydrogenases of ancient bacteria to triggers of apoptosis in vertebrates.Biochimica et biophysica actaReview
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5 authors at 4 institutions in 1 country.
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No grant is acknowledged in the PubMed record.
Abstract
Oxidoreductases of the cytochrome bc(1)/b(6)f family transfer electrons from a liposoluble quinol to a soluble acceptor protein and contribute to the formation of a transmembrane electrochemical potential. The crystal structure of cyt b(6)f has revealed the presence in the Q(i) site of an atypical c-type heme, heme c(i). Surprisingly, the protein does not provide any axial ligand to the iron of this heme, and its surrounding structure suggests it can be accessed by exogenous ligand. In this work we describe a mutagenesis approach aimed at characterizing the c(i) heme and its interaction with the Q(i) site environment. We engineered a mutant of Chlamydomonas reinhardtii in which Phe(40) from subunit IV was substituted by a tyrosine. This results in a dramatic slowing down of the reoxidation of the b hemes under single flash excitation, suggesting hindered accessibility of the heme to its quinone substrate. This modified accessibility likely originates from the ligation of the heme iron by the phenol(ate) side chain introduced by the mutation. Indeed, it also results in a marked downshift of the c(i) heme midpoint potential (from +100 mV to -200 mV at pH 7). Yet the overall turnover rate of the mutant cytochrome b(6)f complex under continuous illumination was found similar to the wild type one, both in vitro and in vivo. We propose that, in the mutant, a change in the ligation state of the heme upon its reduction could act as a redox switch that would control the accessibility of the substrate to the heme and trigger the catalysis.
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