Multiple haem lyase genes indicate substrate specificity in cytochrome <i>c</i> biogenesis

Hartshorne, S.; Richardson, David J.; Simon, Jörg

doi:10.1042/bst0340146

Cited by 31 publications

(45 citation statements)

References 22 publications

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“…We concur that the feature of apocytochromes c recognized by CcsBA is the CXXCH motif. Note that rare “alternative” CcsBA synthetases have been shown to recognize motifs other than CXXCH, such as CXXCK and CX15CH [53, 54], but that here we have studied the more common system II CcsBA.…”

Section: Resultsmentioning

confidence: 99%

Thiol redox requirements and substrate specificities of recombinant cytochrome c assembly systems II and III

Richard-Fogal

Francisco

Frawley

et al. 2012

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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The reconstitution of biosynthetic pathways from heterologous hosts can help define the minimal genetic requirements for pathway function and facilitate detailed mechanistic studies. Each of the three pathways for the assembly of cytochrome c in nature (called systems I, II, and III) has been shown to function recombinantly in Escherichia coli, covalently attaching heme to the cysteine residues of a CXXCH motif of a c-type cytochrome. However, recombinant systems I (CcmABCDEFGH) and II (CcsBA) function in the E. coli periplasm, while recombinant system III (CCHL) attaches heme to its cognate receptor in the cytoplasm of E. coli, which makes direct comparisons between the three systems difficult. Here we show that the human CCHL (with a secretion signal) attaches heme to the human cytochrome c (with a signal sequence) in the E.coli periplasm, which is bioenergetically (p-side) analogous to the mitochondrial intermembrane space. The human CCHL is specific for the human cytochrome c, whereas recombinant system II can attach heme to multiple non-cognate c-type cytochromes (possessing the CXXCH motif.) We also show that the recombinant periplasmic systems II and III use components of the natural E.coli periplasmic DsbC/DsbD thiol-reduction pathway.

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Section: Resultsmentioning

confidence: 99%

Thiol redox requirements and substrate specificities of recombinant cytochrome c assembly systems II and III

Richard-Fogal

Francisco

Frawley

et al. 2012

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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“…c-Type cytochromes require biogenesis systems for their formation and several such systems have been identified in different organisms [3][4][5][6][7]. There are exceptions to this characteristic motif, which include CXXCK variants, as well as those with more than two amino acids between the cysteine residues; some of these require specialized biogenesis systems [8].…”

Section: Introductionmentioning

confidence: 99%

Avoidance of the cytochrome c biogenesis system by periplasmic CXXCH motifs

Mavridou

Braun²,

Thöny‐Meyer³

et al. 2008

Biochemical Society Transactions

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The CXXCH motif is usually recognized in the bacterial periplasm as a haem attachment site in apocytochromes c. There is evidence that the Escherichia coli Ccm (cytochrome c maturation) system recognizes little more than the CXXCH sequence. A limited number of periplasmic proteins have this motif and yet are not c-type cytochromes. To explore how unwanted haem attachment to CXXCH might be avoided, and to determine whether haem attachment to the surface of a non-cytochrome protein would be possible, we converted the active-site CXXCK motif of a thioredoxin-like protein into CXXCH, the C-terminal domain of the transmembrane oxidoreductase DsbD (cDsbD). The E. coli Ccm system was found to catalyse haem attachment to a very small percentage of the resultant protein ( approximately 0.2%). We argue that cDsbD folds sufficiently rapidly that only a small fraction fails to avoid the Ccm system, in contrast with bona fide c-type cytochromes that only adopt their tertiary structure following haem attachment. We also demonstrate covalent haem attachment at a low level in vivo to the periplasmic disulfide isomerase DsbC, which contains a native CXXCH motif. These observations provide insight into substrate recognition by the Ccm system and expand our understanding of the requirements for covalent haem attachment to proteins. The possible evolutionary relationship between thioredoxins and c-type cytochromes is discussed.

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“…The apocytochrome c recognition motif for system I has been much studied and appears to be only the CXXCH motif (6-8, 13, 14, 29), with the caveat that CXXXCH may also be used (130). Some variants of system I (e.g., NrfEFG [51], which is related to CcmFGH) and system II (CcsBA) recognize slightly altered apocytochrome c signature motifs such as CXXCK (51,74,117) or CX15CH (73). These variants are likely to play major roles in the future in understanding of the apocytochrome c recognition determinants and the features of the substrate and synthetases that are important for such.…”

Section: System IV and Othersmentioning

confidence: 99%

CytochromecBiogenesis: Mechanisms for Covalent Modifications and Trafficking of Heme and for Heme-Iron Redox Control

Kranz¹,

Richard-Fogal²,

Taylor

et al. 2009

Microbiol Mol Biol Rev

235

372

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SUMMARY Heme is the prosthetic group for cytochromes, which are directly involved in oxidation/reduction reactions inside and outside the cell. Many cytochromes contain heme with covalent additions at one or both vinyl groups. These include farnesylation at one vinyl in hemes o and a and thioether linkages to each vinyl in cytochrome c (at CXXCH of the protein). Here we review the mechanisms for these covalent attachments, with emphasis on the three unique cytochrome c assembly pathways called systems I, II, and III. All proteins in system I (called Ccm proteins) and system II (Ccs proteins) are integral membrane proteins. Recent biochemical analyses suggest mechanisms for heme channeling to the outside, heme-iron redox control, and attachment to the CXXCH. For system II, the CcsB and CcsA proteins form a cytochrome c synthetase complex which specifically channels heme to an external heme binding domain; in this conserved tryptophan-rich “WWD domain” (in CcsA), the heme is maintained in the reduced state by two external histidines and then ligated to the CXXCH motif. In system I, a two-step process is described. Step 1 is the CcmABCD-mediated synthesis and release of oxidized holoCcmE (heme in the Fe+3 state). We describe how external histidines in CcmC are involved in heme attachment to CcmE, and the chemical mechanism to form oxidized holoCcmE is discussed. Step 2 includes the CcmFH-mediated reduction (to Fe+2) of holoCcmE and ligation of the heme to CXXCH. The evolutionary and ecological advantages for each system are discussed with respect to iron limitation and oxidizing environments.

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Multiple haem lyase genes indicate substrate specificity in cytochrome c biogenesis

Cited by 31 publications

References 22 publications

Thiol redox requirements and substrate specificities of recombinant cytochrome c assembly systems II and III

Thiol redox requirements and substrate specificities of recombinant cytochrome c assembly systems II and III

Avoidance of the cytochrome c biogenesis system by periplasmic CXXCH motifs

CytochromecBiogenesis: Mechanisms for Covalent Modifications and Trafficking of Heme and for Heme-Iron Redox Control

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