Bacillus stearothermophilus qcr Operon Encoding Rieske FeS Protein, Cytochrome b6, and a Novel-type Cytochrome c1 of Quinol-cytochrome c Reductase

Sone, Nobuhito; Tsuchiya, Naofumi; Inoue, Masatomo; Noguchi, Shunsuke

doi:10.1074/jbc.271.21.12457

Cited by 38 publications

(21 citation statements)

References 42 publications

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“…This operon encodes menaquinol:cytochrome c oxidoreductase (the bc complex), which contains a diheme cytochrome b (QcrB; 224 residues) and a monoheme cytochrome c (QcrC; 255 residues) subunit. B. subtilis Qcr mutant data (51, 52) combined with results for Bacillus strain PS3 (18,43) and Bacillus stearothermophilus (41) suggest that the labeled 22-and 29-kDa polypeptides correspond to QcrB and QcrC, respectively.…”

Section: Resultsmentioning

confidence: 99%

Bacillus subtilis CcdA-defective mutants are blocked in a late step of cytochrome c biogenesis

1997

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Cytochromes of the c type contain covalently bound heme. In bacteria, they are located on the outside of the cytoplasmic membrane. Cytochrome c synthesis involves export of heme and apocytochrome across the cytoplasmic membrane followed by ligation of heme to the polypeptide. Using radioactive protoheme IX produced in Escherichia coli, we show that Bacillus subtilis can use heme from the growth medium for cytochrome c synthesis. The B. subtilis ccdA gene encodes a 26-kDa integral membrane protein which is required for cytochrome c synthesis (T. Schiött et al., J. Bacteriol. 179:1962-1973, 1997). In this work, we analyzed the stage at which cytochrome c synthesis is blocked in a ccdA deletion mutant. The following steps were found to be normal in the mutant: (i) transcription and translation of cytochrome c structural genes, (ii) translocation of apocytochrome across the cytoplasmic membrane, and (iii) heme transport from the cytoplasm to cytochrome polypeptide on the outer side of the cytoplasmic membrane. It is concluded that CcdA is required for a late step in the cytochrome c synthesis pathway.

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Section: Resultsmentioning

confidence: 99%

Bacillus subtilis CcdA-defective mutants are blocked in a late step of cytochrome c biogenesis

1997

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“…The ferredoxin/FNR‐dependent cyclic electron transfer pathway as an n ‐side branch in the b 6 f complex, as well as the presence of the unique heme c n suggested that the special function of heme c n is related to the pathway of PSI‐linked cyclic electron transport, which is not present in the bc 1 complex. However, biochemical (72–76), sequence (1,77) and phylogenetic (78) analysis shows that cytochrome b 6 and the Rieske protein are present in the primitive nonphotosynthetic firmicutes, as is the heme c n (76). Therefore, heme c n must have another function in the “dark” metabolism of these organisms that certainly do not carry out PSI‐linked cyclic electron transport.…”

Section: Structure–functionmentioning

confidence: 99%

Structure–Function of the Cytochrome b₆f Complex^†

Baniulis

Yamashita

Zhang

et al. 2008

Photochem & Photobiology

132

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The structure and function of the cytochrome b6 f complex is considered in the context of recent crystal structures of the complex as an eight subunit, 220 kDa symmetric dimeric complex obtained from the thermophilic cyanobacterium, Mastigocladus laminosus, and the green alga, Chlamydomonas reinhardtii. A major problem confronted in crystallization of the cyanobacterial complex, proteolysis of three of the subunits, is discussed along with initial efforts to identify the protease. The evolution of these cytochrome complexes is illustrated by conservation of the hydrophobic heme‐binding transmembrane domain of the cyt b polypeptide between b6 f and bc1 complexes, and the rubredoxin‐like membrane proximal domain of the Rieske [2Fe‐2S] protein. Pathways of coupled electron and proton transfer are discussed in the framework of a modified Q cycle, in which the heme cn, not found in the bc1 complex, but electronically tightly coupled to the heme bn of the b6 f complex, is included. Crystal structures of the cyanobacterial complex with the quinone analogue inhibitors, NQNO or tridecyl‐stigmatellin, show the latter to be ligands of heme cn, implicating heme cn as an n‐side plastoquinone reductase. Existing questions include (a) the details of the shuttle of: (i) the [2Fe‐2S] protein between the membrane‐bound PQH2 electron/H+ donor and the cytochrome f acceptor to complete the p‐side electron transfer circuit; (ii) PQ/PQH2 between n‐ and p‐sides of the complex across the intermonomer quinone exchange cavity, through the narrow portal connecting the cavity with the p‐side [2Fe‐2S] niche; (b) the role of the n‐side of the b6 f complex and heme cn in regulation of the relative rates of noncyclic and cyclic electron transfer. 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.

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“…In all these cases the cytochrome bc complex transfers electrons from quinol to a small electron carrier protein (cytochromes or copper proteins) and couples electron transfer to the translocation of protons across the membrane thereby creating a proton gradient. Recent studies on phylogenetically diverse species have demonstrated that both the structural composition and basic functional parameters of cytochrome bc complexes are much more divergent than previously assumed [2–5]. The representatives encountered in proteobacteria and mitochondria, however, constitute the relatively uniform subgroup of the cytochrome bc 1 complexes.…”

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confidence: 99%

The cytochrome bc₁ complex from Rhodovulum sulfidophilum is a dimer with six quinones per monomer and an additional 6‐kDa component

Montoya¹,

Kaat²,

Rodgers³

et al. 1999

European Journal of Biochemistry

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A highly active, large-scale preparation of cytochrome bc 1 complex has been obtained from the photosynthetic purple bacterium Rhodovulum (Rhv.) sulfidophilum. It has been characterized using mass spectrometry, quinone and lipid analysis as well as inhibitor binding. About 35 mg of pure complex can be obtained from 1 g of membrane protein. EPR spectroscopy and optical titrations have been used to obtain the redox midpoint potentials of the cofactors. The E m -value of 310 mV for the Rieske protein is the most positive midpoint potential for this protein in a bc 1 complex so far. The bc 1 complex from Rhv. sulfidophilum is very stable and consists of three subunits and a 6-kDa polypeptide. The complex appears as a dimer in solution and contains six quinone molecules per monomer which are tightly bound. EPR spectroscopy shows that the Q o site is highly occupied. High detergent concentrations convert the complex into an inactive, monomeric form that has lost the Rieske protein as well as the quinones and the 6-kDa component.

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Bacillus stearothermophilus qcr Operon Encoding Rieske FeS Protein, Cytochrome b6, and a Novel-type Cytochrome c1 of Quinol-cytochrome c Reductase

Cited by 38 publications

References 42 publications

Bacillus subtilis CcdA-defective mutants are blocked in a late step of cytochrome c biogenesis

Bacillus subtilis CcdA-defective mutants are blocked in a late step of cytochrome c biogenesis

Structure–Function of the Cytochrome b₆f Complex^†

The cytochrome bc₁ complex from Rhodovulum sulfidophilum is a dimer with six quinones per monomer and an additional 6‐kDa component

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Bacillus stearothermophilus qcr Operon Encoding Rieske FeS Protein, Cytochrome b6, and a Novel-type Cytochrome c1 of Quinol-cytochrome c Reductase

Cited by 38 publications

References 42 publications

Bacillus subtilis CcdA-defective mutants are blocked in a late step of cytochrome c biogenesis

Bacillus subtilis CcdA-defective mutants are blocked in a late step of cytochrome c biogenesis

Structure–Function of the Cytochrome b6f Complex†

The cytochrome bc1 complex from Rhodovulum sulfidophilum is a dimer with six quinones per monomer and an additional 6‐kDa component

Contact Info

Product

Resources

About

Structure–Function of the Cytochrome b₆f Complex^†

The cytochrome bc₁ complex from Rhodovulum sulfidophilum is a dimer with six quinones per monomer and an additional 6‐kDa component