The role of ResA in type II cytochrome c maturation

2005 ◽  
Vol 33 (1) ◽  
pp. 149-151 ◽  
Author(s):  
A. Crow ◽  
N.E. Le Brun ◽  
A. Oubrie

Numerous bacterial proteins involved in the nitrogen cycle, and other processes, require c-type haem as a cofactor. c-type cytochromes are formed by covalent attachment of haem to the conserved CXXCH motif. Here, we briefly review what is presently known about cytochrome c maturation in Bacillus subtilis with particular emphasis on the crystal structures of ResA.

2006 ◽  
Vol 34 (1) ◽  
pp. 91-93 ◽  
Author(s):  
J.W.A. Allen ◽  
S.J. Ferguson

c-Type cytochromes are characterized by covalent attachment of haem to protein through thioether bonds between the vinyl groups of the haem and the thiols of a Cys-Xaa-Xaa-Cys-His motif. Proteins of this type play crucial roles in the biochemistry of the nitrogen cycle. Many Gram-negative bacteria use the Ccm (cytochrome c maturation) proteins for the post-translational haem attachment to their c-type cytochromes. The Ccm system can correctly mature c-type cytochromes with CCXXCH, CCXCH, CXCCH and CXXCHC motifs, even though these are not found naturally and the extra cysteine might, in principle, disrupt the biogenesis proteins. The non-occurrence of these motifs probably relates to the destructive chemistry that can occur if a free thiol reacts with haem iron to generate a radical.


2006 ◽  
Vol 34 (1) ◽  
pp. 150-151 ◽  
Author(s):  
J.W.A. Allen ◽  
S.J. Ferguson

c-Type cytochromes are characterized by covalent attachment of haem to protein through thioether bonds between the vinyl groups of the haem and the thiols of a CXXCH motif. Proteins of this type play crucial roles in the biochemistry of the nitrogen cycle. Many Gram-negative bacteria use the Ccm (cytochrome c maturation) proteins for the post-translational haem attachment to their c-type cytochromes; in the present paper, we discuss the substrate specificity of the Ccm apparatus. The main conclusion is that the feature recognized and required in the apocytochrome is simply the two cysteines and the histidine of the haem-binding motif.


2009 ◽  
Vol 419 (1) ◽  
pp. 177-186 ◽  
Author(s):  
James W. A. Allen ◽  
Elizabeth B. Sawyer ◽  
Michael L. Ginger ◽  
Paul D. Barker ◽  
Stuart J. Ferguson

c-type cytochromes are normally characterized by covalent attachment of the iron cofactor haem to protein through two thioether bonds between the vinyl groups of the haem and the thiol groups of a CXXCH (Cys–Xaa–Xaa–Cys–His) motif. In cells, the haem attachment is an enzyme-catalysed post-translational modification. We have previously shown that co-expression of a variant of Escherichia coli cytochrome b562 containing a CXXCH haem-binding motif with the E. coli Ccm (cytochrome c maturation) proteins resulted in homogeneous maturation of a correctly formed c-type cytochrome. In contrast, in the absence of the Ccm apparatus, the product holocytochrome was heterogeneous, the main species having haem inverted and attached through only one thioether bond. In the present study we use further variants of cytochrome b562 to investigate the substrate specificity of the E. coli Ccm apparatus. The system can mature c-type cytochromes with CCXXCH, CCXCH, CXCCH and CXXCHC motifs, even though these are not found naturally and the extra cysteine residue might, in principle, disrupt the biogenesis proteins which must interact intricately with disulfide-bond oxidizing and reducing proteins in the E. coli periplasm. The Ccm proteins can also attach haem to motifs of the type CXnCH where n ranges from 2 to 6. For n=3 and 4, the haem attachment was correct and homogeneous, but for higher values of n the holocytochromes displayed oxidative addition of sulfur and/or oxygen atoms associated with the covalent haem-attachment process. The implications of our observations for the haem-attachment reaction, for genome analyses and for the substrate specificity of the Ccm system, are discussed.


2003 ◽  
Vol 375 (3) ◽  
pp. 721-728 ◽  
Author(s):  
James W. A. ALLEN ◽  
Stuart J. FERGUSON

Cytochromes c are typically characterized by the covalent attachment of haem to polypeptide through two thioether bonds with the cysteine residues of a Cys-Xaa-Xaa-Cys-His peptide motif. In many Gram-negative bacteria, the haem is attached to the polypeptide by the periplasmically functioning cytochrome c maturation (Ccm) proteins. Exceptionally, Hydrogenobacter thermophilus cytochrome c552 can be expressed as a stable holocytochrome both in the cytoplasm of Escherichia coli in an apparently uncatalysed reaction and also in the periplasm in a Ccm-mediated reaction. In the present study we show that a Met60→Ala variant of c552, which does not have the usual distal methionine ligand to the haem iron of the mature cytochrome, can be made in the periplasm by the Ccm system. However, no holocytochrome could be detected when this variant was expressed cytoplasmically. These data highlight differences between the two modes of cytochrome c assembly. In addition, we report investigations of haem attachment to cytochromes altered to have the special Cys-Trp-Ser-Cys-Lys haem-binding motif, and Cys-Trp-Ser-Cys-His and Cys-Trp-Ala-Cys-His analogues, of the active-site haem of nitrite reductase NrfA.


2013 ◽  
Vol 13 (1) ◽  
pp. 265 ◽  
Author(s):  
Christina Ferousi ◽  
Daan R Speth ◽  
Joachim Reimann ◽  
Huub JM Op den Camp ◽  
James WA Allen ◽  
...  

mBio ◽  
2013 ◽  
Vol 4 (5) ◽  
Author(s):  
Jennifer L. Small ◽  
Sae Woong Park ◽  
Bavesh D. Kana ◽  
Thomas R. Ioerger ◽  
James C. Sacchettini ◽  
...  

ABSTRACTMycobacterium tuberculosisdepends on aerobic respiration for growth and utilizes anaa3-type cytochromecoxidase for terminal electron transfer. Cytochromecmaturation in bacteria requires covalent attachment of heme to apocytochromec, which occurs outside the cytoplasmic membrane. We demonstrate that inM. tuberculosisthe thioredoxin-like protein Rv3673c, which we named CcsX, is required for heme insertion in cytochromec. Inactivation of CcsX resulted in loss ofc-type heme absorbance, impaired growth and virulence ofM. tuberculosis, and induced cytochromebdoxidase. This suggests that the bioenergetically less efficientbdoxidase can compensate for deficient cytochromecoxidase activity, highlighting the flexibility of theM. tuberculosisrespiratory chain. A spontaneous mutation in the active site of vitamin K epoxide reductase (VKOR) suppressed phenotypes of the CcsX mutant and abrogated the activity of the disulfide bond-dependent alkaline phosphatase, which shows that VKOR is the major disulfide bond catalyzing protein in the periplasm ofM. tuberculosis.IMPORTANCEMycobacterium tuberculosisrequires oxygen for growth; however, the biogenesis of respiratory chain components in mycobacteria has not been explored. Here, we identified a periplasmic thioredoxin, CcsX, necessary for heme insertion into cytochromec. We investigated the consequences of disrupting cytochromecmaturation (CCM) for growth and survival ofM. tuberculosis in vitroand for its pathogenesis. Appearance of a second-site suppressor mutation in the periplasmic disulfide bond catalyzing protein VKOR indicates the strong selective pressure for a functional cytochromecoxidase. The observation thatM. tuberculosisis able to partially compensate for defective CCM by upregulation of the cytochromebdoxidase exposes a functional role of this alternative terminal oxidase under normal aerobic conditions and during pathogenesis. This suggests that targeting both oxidases simultaneously might be required to effectively disrupt respiration inM. tuberculosis.


2005 ◽  
Vol 389 (2) ◽  
pp. 587-592 ◽  
Author(s):  
James W. A. Allen ◽  
Nicholas Leach ◽  
Stuart J. Ferguson

c-type cytochromes are characterized by covalent attachment of haem to the protein by two thioether bonds formed between the haem vinyl groups and the cysteine sulphurs in a CXXCH peptide motif. In Escherichia coli and many other Gram-negative bacteria, this post-translational haem attachment is catalysed by the Ccm (cytochrome c maturation) system. The features of the apocytochrome substrate required and recognized by the Ccm apparatus are uncertain. In the present study, we report investigations of maturation of cytochrome b562 variants containing CXXCR, CXXCK or CXXCM haem-binding motifs. None of them showed any evidence for correct maturation by the Ccm system. However, we have determined, for each variant, that the proteins (i) were expressed in large amounts, (ii) could bind haem in vivo and/or in vitro and (iii) were not degraded in the cell. Together with previous observations, these results strongly suggest that the apocytochrome substrate feature recognized by the Ccm system is simply the two cysteine residues and the histidine of the CXXCH haem-binding motif. Using the same experimental approach, we have also investigated a cytochrome b562 variant containing the special CWSCK motif that binds the active-site haem of E. coli nitrite reductase NrfA. Whereas a CWSCH analogue was matured by the Ccm apparatus in large amounts, the CWSCK form was not detectably matured either by the Ccm system or by the dedicated Nrf biogenesis proteins, implying that the substrate recognition features for haem attachment in NrfA may be more extensive than the CWSCK motif.


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