title: Compensatory thio-redox interactions between DsbA, CcdA and CcmG unveil the apocytochrome c holdase role of CcmG during cytochrome c maturation.
abstract: During cytochrome c maturation (Ccm), the DsbA-dependent thio-oxidative protein-folding pathway is thought to introduce a disulphide bond into the haem-binding motif of apocytochromes c. This disulphide bond is believed to be reduced through a thio-reductive pathway involving the Ccm components CcdA (DsbD), CcmG and CcmH. Here, we show in Rhodobacter capsulatus that in the absence of DsbA cytochrome c levels were decreased and CcdA or CcmG or the putative glutathione transporter CydDC was not needed for Ccm. This decrease was not due to overproduction of the periplasmic protease DegP as a secondary effect of DsbA absence. In contrast, CcmH was absolutely necessary regardless of DsbA, indicating that compensatory thio-redox interactions excluded it. Remarkably, the double (DsbA-CcmG) and triple (DsbA-CcmG-CcdA) mutants produced cytochromes c at lower levels than the DsbA-null mutants, unless they contained a CcmG derivative (CcmG*) lacking its thio-reductive activity. Purified CcmG* can bind apocytochrome c in vitro, revealing for the first time a thiol-independent, direct interaction between apocytochrome c and CcmG. Furthermore, elimination of the thio-redox components does not abolish cytochrome c production, restricting the number of Ccm components essential for haem-apocyt c ligation per se during Ccm.
authors.affiliation: Department of Biology, Plant Science Institute, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Serdar
authors.initials: S
authors.lastname: Turkarslan
authors.forename: Carsten
authors.initials: C
authors.lastname: Sanders
authors.forename: Seda
authors.initials: S
authors.lastname: Ekici
authors.forename: Fevzi
authors.initials: F
authors.lastname: Daldal
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D045304:Cytochromes c / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010084:Oxidation-Reduction; D011490:Protein Disulfide Reductase (Glutathione) / Q000235:genetics / Q000378:metabolism*; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism*; D016354:Rhodobacter capsulatus / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C068355:CcdA protein, Bacteria; D029968:Escherichia coli Proteins; D045304:Cytochromes c; C485980:Ccmg protein, E coli; D011490:Protein Disulfide Reductase (Glutathione); D019704:Protein Disulfide-Isomerases
references.citation: Mol Microbiol. 2001 Jul;41(1):241-6
references.pmid: 11454216
references.citation: J Mol Biol. 1997 Sep 5;271(5):679-92
references.pmid: 9299319
references.citation: Arch Microbiol. 1999 Jan;171(2):92-100
references.pmid: 9914305
references.citation: Structure. 1999 Dec 15;7(12):R281-90
references.pmid: 10647174
references.citation: J Bacteriol. 2002 Mar;184(5):1423-9
references.pmid: 11844773
references.citation: J Mol Biol. 1987 May 5;195(1):13-24
references.pmid: 2821268
references.citation: J Bacteriol. 2004 Jun;186(12):4030-3
references.pmid: 15175318
references.citation: Gene. 1988 Oct 15;70(1):191-7
references.pmid: 2853689
references.citation: J Bacteriol. 2007 Sep;189(17):6253-9
references.pmid: 17616605
references.citation: Biochim Biophys Acta. 2000 Aug 15;1459(2-3):316-24
references.pmid: 11004446
references.citation: J Bacteriol. 2005 Jun;187(12):4245-56
references.pmid: 15937187
references.citation: J Bacteriol. 1987 May;169(5):2107-12
references.pmid: 3032907
references.citation: J Biol Chem. 2003 Dec 26;278(52):52075-83
references.pmid: 14534316
references.citation: Nature. 1970 Aug 15;227(5259):680-5
references.pmid: 5432063
references.citation: Proc Natl Acad Sci U S A. 2002 Jun 11;99(12):7872-6
references.pmid: 12060734
references.citation: Mol Cell Proteomics. 2008 May;7(5):875-90
references.pmid: 18174153
references.citation: Mol Microbiol. 1998 Jul;29(2):383-96
references.pmid: 9720859
references.citation: J Biol Chem. 2005 Sep 16;280(37):32254-61
references.pmid: 16040611
references.citation: FEMS Microbiol Lett. 1994 Apr 1;117(2):217-23
references.pmid: 8181727
references.citation: J Bacteriol. 1992 Apr;174(7):2352-60
references.pmid: 1551852
references.citation: Mol Gen Genet. 1996 Nov 27;253(1-2):95-102
references.pmid: 9003292
references.citation: J Biol Chem. 1980 Mar 25;255(6):2427-32
references.pmid: 7358679
references.citation: Mol Microbiol. 2000 Jan;35(1):123-38
references.pmid: 10632883
references.citation: Biochem Soc Trans. 2002 Aug;30(4):633-8
references.pmid: 12196152
references.citation: Genes Dev. 1992 Feb;6(2):268-83
references.pmid: 1310666
references.citation: Proc Natl Acad Sci U S A. 2006 Mar 21;103(12):4410-5
references.pmid: 16537372
references.citation: FEBS Lett. 2008 Sep 3;582(20):3067-72
references.pmid: 18687332
references.citation: J Mol Biol. 1979 Jun 25;131(2):157-68
references.pmid: 490646
references.citation: J Biol Chem. 2004 May 28;279(22):23654-60
references.pmid: 15047692
references.citation: J Bacteriol. 1998 Apr;180(7):1947-50
references.pmid: 9537397
references.citation: Gene. 1984 Sep;29(3):303-13
references.pmid: 6237955
references.citation: Proc Natl Acad Sci U S A. 1986 Apr;83(7):2012-6
references.pmid: 16593675
references.citation: Mol Microbiol. 2002 Nov;46(4):1069-80
references.pmid: 12421312
references.citation: Philos Trans R Soc Lond B Biol Sci. 2003 Jan 29;358(1429):255-66
references.pmid: 12594933
references.citation: J Bacteriol. 2003 Jun;185(11):3361-72
references.pmid: 12754234
references.citation: Anal Biochem. 1976 Sep;75(1):168-76
references.pmid: 822747
references.citation: J Gen Microbiol. 1960 Jun;22:778-85
references.pmid: 14447230
references.citation: J Bacteriol. 1998 Feb;180(4):969-78
references.pmid: 9473054
references.citation: Biochemistry. 1994 Mar 15;33(10):3120-7
references.pmid: 8130227
references.citation: J Bacteriol. 2007 Feb;189(3):789-800
references.pmid: 17122341
references.citation: EMBO J. 2002 Aug 1;21(15):3960-9
references.pmid: 12145197
references.citation: Plasmid. 1985 Mar;13(2):149-53
references.pmid: 2987994
references.citation: Arch Microbiol. 1993;160(6):413-23
references.pmid: 8297207
references.citation: Structure. 2002 Jul;10(7):973-9
references.pmid: 12121652
references.citation: Cell. 2000 Nov 22;103(5):769-79
references.pmid: 11114333
references.citation: Anal Biochem. 1987 Nov 1;166(2):368-79
references.pmid: 2449095
references.citation: J Biol Chem. 2002 Mar 8;277(10):7657-63
references.pmid: 11744735
references.citation: J Mol Biol. 1990 Oct 5;215(3):403-10
references.pmid: 2231712
references.citation: J Biol Chem. 1951 Nov;193(1):265-75
references.pmid: 14907713
references.citation: J Biol Chem. 2007 Sep 14;282(37):27012-27019
references.pmid: 17623665
references.citation: Proc Natl Acad Sci U S A. 1993 Mar 15;90(6):2179-83
references.pmid: 8384715
references.citation: Biosci Biotechnol Biochem. 2005 Jul;69(7):1418-21
references.pmid: 16041151