Disease relevance of cytM

• Primary structure of cotranscribed genes encoding the Rieske Fe-S and cytochrome f proteins of the cyanobacterium Nostoc PCC 7906 [1].
• The Rieske Fe-S/cytochrome f gene pair thus represents an example of clustering and cotranscription in cyanobacteria of functionally related genes that, in photosynthetic eukaryotes, reside on separate nuclear and plastid genomes [1].
• Cytochrome c oxidase genes required for nitrogenase activity and diazotrophic growth in Anabaena sp. PCC 7120 [2].
• Recombinant, ferric heme-reconstituted Synechocystis sp. PCC 6803 hemoglobin is a low-spin complex whose endogenous hexacoordination gives rise to optical and NMR characteristics reminiscent of cytochrome b(5) [Scott, N. L., and Lecomte, J. T. J. (2000) Protein Sci. 9, 587-597] [3].

High impact information on cytM

• The thylakoid membrane cytochrome b6-f complex (plastoquinol:oxidized-plastocyanin oxidoreductase, EC 1.10.99.1) catalyzes electron-transfer and proton-translocation reactions essential for oxygenic photosynthesis [1].
• The C terminus of the Rieske Fe-S protein contains cysteine and histidine residues (probable ligands for the Fe2S2 center) in two peptides, Cys-Thr-His-Leu-Gly-Cys-Val and Cys-Pro-Cys-His-Gly-Ser, which have been conserved in spinach and in the five available Rieske Fe-S sequences from the mitochondrial-type cytochrome b-c1 complexes [1].
• The data show that the hydrophobic patch surrounding tyrosine 1 in cytochrome f docks the hydrophobic patch of plastocyanin [4].
• These data suggest that a single set of cytochrome b6-f proteins function in the different types of membranes found in Nostoc vegetative and heterocyst cells [5].
• Characterization of two operons encoding the cytochrome b6-f complex of the cyanobacterium Nostoc PCC 7906. Highly conserved sequences but different gene organization than in chloroplasts [5].

Chemical compound and disease context of cytM

• Photoautotrophically grown cyanobacterium Nostoc sp. strain Mac (PCC 8009) released up to about 10 nmol of a c-type cytochrome per ml packed cells after treatment with EDTA under conditions that left the plasma membrane absolutely intact as judged from the absence of cytosolic proteins in the supernatant [6].

Biological context of cytM

• Hydropathy analyses revealed five potential membrane spans in cytochrome b6 and three in the subunit IV protein, consistent with the profiles observed for the chloroplast proteins and the related cytochrome b proteins of cytochrome b-c1 complexes [5].
• Respiration is thought to contribute to the diazotrophic metabolism of heterocysts and the genome of the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120 bears three gene clusters putatively encoding cytochrome c oxidases [2].
• The Rieske 2Fe-2S protein is a distinguishing subunit of the photosynthetic electron transport cytochrome b6f complex in chloroplast and cyanobacterial thylakoid membranes [7].
• [(1996) J. Bacteriol. 178, 6587-6598], in which cyanoglobin sequesters oxygen, and presents it to, or is a part of, a terminal cytochrome oxidase complex in Nostoc commune UTEX 584 under microaerobic conditions, when nitrogen fixation, and thus ATP demand, is maximal [8].
• Here, five negatively charged residues of a recombinant form of cytochrome f from Nostoc have been replaced with either neutral or positively charged residues, and the effects of mutations on the kinetics of electron transfer to wild-type and mutant forms of plastocyanin have been measured by laser flash absorption spectroscopy [9].

Associations of cytM with chemical compounds

• At 10-15% O2, the slow, dark reduction of cytochrome b563 was eliminated [10].
• Spectra of the ascorbate reduced cytochrome revealed peaks at 553, 522 and 416 nm [6].
• Effect of NADP on light-induced cytochrome changes in membrane fragments from a blue-green alga [11].

Other interactions of cytM

• In some cyanobacteria and eukaryotic algae, cytochrome c-553 (c-552) and plastocyanin function as alternative electron carriers between the cytochrome b6-f complex and Photosystem I [12].

References