Haem‐delivery proteins in cytochrome <i>c</i> maturation System II

Ahuja, Umesh; Kjelgaard, Peter; Schulz, Benjamin L.; Thöny‐Meyer, Linda; Hederstedt, Lars

doi:10.1111/j.1365-2958.2009.06833.x

Cited by 34 publications

(45 citation statements)

References 39 publications

(52 reference statements)

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“…Taken together, the results described above indicate that the cytochrome components of the bc 1 complex are correctly localized and assembled in the absence of a functional Tat system (since c-heme insertion occurs at the extracytoplasmic side of the mem- brane in bacteria) (16,47). However, the lack of menadiol-dependent reduction of exogenous cytochrome c in the ⌬tatC strain is consistent with an inability to translocate the Rieske iron-sulfur domain of QcrA across the membrane.…”

Section: Resultsmentioning

confidence: 51%

Role of the Twin Arginine Protein Transport Pathway in the Assembly of the Streptomyces coelicolor Cytochrome bc ₁ Complex

2014

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The cytochrome bc 1 -cytochrome aa 3 complexes together comprise one of the major branches of the bacterial aerobic respiratory chain. In actinobacteria, the cytochrome bc 1 complex shows a number of unusual features in comparison to other cytochrome bc 1 complexes. In particular, the Rieske iron-sulfur protein component of this complex, QcrA, is a polytopic rather than a monotopic membrane protein. Bacterial Rieske proteins are usually integrated into the membrane in a folded conformation by the twin arginine protein transport (Tat) pathway. In this study, we show that the activity of the Streptomyces coelicolor M145 cytochrome bc 1 complex is dependent upon an active Tat pathway. However, the polytopic Rieske protein is still integrated into the membrane in a ⌬tatC mutant strain, indicating that a second protein translocation machinery also participates in its assembly. Difference spectroscopy indicated that the cytochrome c component of the complex was correctly assembled in the absence of the Tat machinery. We show that the intact cytochrome bc 1 complex can be isolated from S. coelicolor M145 membranes by affinity chromatography. Surprisingly, a stable cytochrome bc 1 complex containing the Rieske protein can be isolated from membranes even when the Tat system is inactive. These findings strongly suggest that the additional transmembrane segments of the S. coelicolor Rieske protein mediate hydrophobic interactions with one or both of the cytochrome subunits.

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Section: Resultsmentioning

confidence: 51%

Role of the Twin Arginine Protein Transport Pathway in the Assembly of the Streptomyces coelicolor Cytochrome bc ₁ Complex

2014

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“…The increased virulence gene expression and hemolysis in the ⌬resBC strain relative to the strain missing all known c-type cytochromes was surprising given that the only known functions of ResBC are related to heme delivery to c-type cytochromes (29,30). Several possibilities may explain this discrepancy.…”

Section: Discussionmentioning

confidence: 64%

“…The apo-cytochrome c is secreted across the membrane by the Sec translocation system. At the membrane, the oxidoreductase ResA reduces cysteine residues in the heme binding pocket of apo-cytochrome (28), while ResB and ResC transport and covalently attach heme to the reduced apo-cytochrome to generate the final, active form of cytochrome c (29,30). Loss of ResB and ResC in B. anthracis also results in increased toxin gene production through AtxA.…”

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confidence: 99%

Cytochromec₅₅₁and the CytochromecMaturation Pathway Affect Virulence Gene Expression in Bacillus cereus ATCC 14579

Han¹,

Sullivan²,

Wilson³

2014

J. Bacteriol.

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Loss of the cytochrome c maturation system in Bacillus cereus results in increased transcription of the major enterotoxin genes nhe, hbl, and cytK and the virulence regulator plcR. Increased virulence factor production occurs at 37°C under aerobic conditions, similar to previous findings in Bacillus anthracis. Unlike B. anthracis, much of the increased virulence gene expression can be attributed to loss of only c 551 , one of the two small c-type cytochromes. Additional virulence factor expression occurs with loss of resBC, encoding cytochrome c maturation proteins, independently of the presence of the c-type cytochrome genes. Hemolytic activity of strains missing either cccB or resBC is increased relative to that in the parental strain, while sporulation efficiency is unaffected in the mutants. Increased virulence gene expression in the ⌬cccB and ⌬resBC mutants occurs only in the presence of an intact plcR gene, indicating that this process is PlcR dependent. These findings suggest a new mode of regulation of B. cereus virulence and reveal intriguing similarities and differences in virulence regulation between B. cereus and B. anthracis.

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“…The apocytochrome c is secreted across the membrane by the Sec translocation system. At the membrane, the cytochrome c maturation protein ResA reduces cysteine residues in the heme binding pocket of apocytochrome (14), while ResB and ResC transport and covalently attach heme to the reduced apocytochrome to generate the final, active form of cytochrome c (15,16).…”

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confidence: 99%

The Two CcdA Proteins of Bacillus anthracis Differentially Affect Virulence Gene Expression and Sporulation

Han¹,

Wilson²

2013

Journal of Bacteriology

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The cytochrome c maturation system influences the expression of virulence factors in Bacillus anthracis. B. anthracis carries two copies of the ccdA gene, encoding predicted thiol-disulfide oxidoreductases that contribute to cytochrome c maturation, while the closely related organism Bacillus subtilis carries only one copy of ccdA. To investigate the roles of the two ccdA gene copies in B. anthracis, strains were constructed without each ccdA gene, and one strain was constructed without both copies simultaneously. Loss of both ccdA genes results in a reduction of cytochrome c production, an increase in virulence factor expression, and a reduction in sporulation efficiency. Complementation and expression analyses indicate that ccdA2 encodes the primary CcdA in B. anthracis, active in all three pathways. While CcdA1 retains activity in cytochrome c maturation and virulence control, it has completely lost its activity in the sporulation pathway. In support of this finding, expression of ccdA1 is strongly reduced when cells are grown under sporulation-inducing conditions. When the activities of CcdA1 and CcdA2 were analyzed in B. subtilis, neither protein retained activity in cytochrome c maturation, but CcdA2 could still function in sporulation. These observations reveal the complexities of thiol-disulfide oxidoreductase function in pathways relevant to virulence and physiology.

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Haem‐delivery proteins in cytochrome c maturation System II

Cited by 34 publications

References 39 publications

Role of the Twin Arginine Protein Transport Pathway in the Assembly of the Streptomyces coelicolor Cytochrome bc ₁ Complex

Role of the Twin Arginine Protein Transport Pathway in the Assembly of the Streptomyces coelicolor Cytochrome bc ₁ Complex

Cytochromec₅₅₁and the CytochromecMaturation Pathway Affect Virulence Gene Expression in Bacillus cereus ATCC 14579

The Two CcdA Proteins of Bacillus anthracis Differentially Affect Virulence Gene Expression and Sporulation

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Haem‐delivery proteins in cytochrome c maturation System II

Cited by 34 publications

References 39 publications

Role of the Twin Arginine Protein Transport Pathway in the Assembly of the Streptomyces coelicolor Cytochrome bc 1 Complex

Role of the Twin Arginine Protein Transport Pathway in the Assembly of the Streptomyces coelicolor Cytochrome bc 1 Complex

Cytochromec551and the CytochromecMaturation Pathway Affect Virulence Gene Expression in Bacillus cereus ATCC 14579

The Two CcdA Proteins of Bacillus anthracis Differentially Affect Virulence Gene Expression and Sporulation

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Role of the Twin Arginine Protein Transport Pathway in the Assembly of the Streptomyces coelicolor Cytochrome bc ₁ Complex

Role of the Twin Arginine Protein Transport Pathway in the Assembly of the Streptomyces coelicolor Cytochrome bc ₁ Complex

Cytochromec₅₅₁and the CytochromecMaturation Pathway Affect Virulence Gene Expression in Bacillus cereus ATCC 14579