title: Dynamics of the His79-heme alkaline transition of yeast iso-1-cytochrome c probed by conformationally gated electron transfer with Co(II)bis(terpyridine).
abstract: Alkaline conformers of cytochrome c may be involved in both its electron transport and apoptotic functions. We use cobalt(II)bis(terpyridine), Co(terpy)2(2+), as a reagent for conformationally gated electron-transfer (gated ET) experiments to study the alkaline conformational transition of K79H variants of yeast iso-1-cytochrome c expressed in Escherichia coli , WT*K79H, with alanine at position 72 and Saccharomyces cerevisiae , yK79H, with trimethyllysine (Tml) at position 72. Co(terpy)2(2+) is well-suited to the 100 ms to 1 s time scale of the His79-mediated alkaline conformational transition of these variants. Reduction of the His79-heme alkaline conformer by Co(terpy)2(2+) occurs primarily by gated ET, which involves conversion to the native state followed by reduction, with a small fraction of the His79-heme alkaline conformer directly reduced by Co(terpy)2(2+). The gated ET experiments show that the mechanism of formation of the His79-heme alkaline conformer involves only two ionizable groups. In previous work, we showed that the mechanism of the His73-mediated alkaline conformational transition requires three ionizable groups. Thus, the mechanism of heme crevice opening depends upon the position of the ligand mediating the process. The microscopic rate constants provided by gated ET studies show that mutation of Tml72 (yK79H variant) in the heme crevice loop to Ala72 (WT*K79H variant) affects the dynamics of heme crevice opening through a small destabilization of both the native conformer and the transition state relative to the His79-heme alkaline conformer. Previous pH jump data had indicated that the Tml72→Ala mutation primarily stabilized the transition state for the His79-mediated alkaline conformational transition.
authors.affiliation: Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana 59812, USA.
authors.forename: Melisa M
authors.initials: MM
authors.lastname: Cherney
authors.forename: Carolyn C
authors.initials: CC
authors.lastname: Junior
authors.forename: Bryan B
authors.initials: BB
authors.lastname: Bergquist
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Bowler
mesh_terms: D000468:Alkalies / Q000737:chemistry / Q000378:metabolism*; D003575:Cytochromes c1 / Q000737:chemistry / Q000378:metabolism*; D004579:Electron Transport; D006418:Heme / Q000737:chemistry / Q000378:metabolism*; D006639:Histidine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D009154:Mutation; D009942:Organometallic Compounds / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013816:Thermodynamics
chemical_list: D000468:Alkalies; D009942:Organometallic Compounds; D006418:Heme; D006639:Histidine; D003575:Cytochromes c1
references.citation: J Am Chem Soc. 2007 Apr 11;129(14):4423-9
references.pmid: 17367139
references.citation: Biochemistry. 2003 Sep 16;42(36):10659-66
references.pmid: 12962490
references.citation: Nature. 2011 Aug 21;477(7362):111-4
references.pmid: 21857680
references.citation: J Biol Chem. 1974 Apr 25;249(8):2624-32
references.pmid: 4362690
references.citation: Eur J Biochem. 1999 Apr;261(2):379-91
references.pmid: 10215847
references.citation: Biochemistry. 1980 Jan 8;19(1):199-207
references.pmid: 6243472
references.citation: Biochemistry. 2005 Dec 27;44(51):16785-95
references.pmid: 16363792
references.citation: J Am Chem Soc. 2005 Jul 13;127(27):9702-3
references.pmid: 15998071
references.citation: Biochemistry. 2008 Dec 23;47(51):13470-80
references.pmid: 19035653
references.citation: J Am Chem Soc. 2011 Dec 14;133(49):19676-9
references.pmid: 22081937
references.citation: Biopolymers. 2013;100(1):114-24
references.pmid: 23335173
references.citation: Biochemistry. 2008 Sep 9;47(36):9667-77
references.pmid: 18702508
references.citation: Biochem Biophys Res Commun. 2003 Dec 19;312(3):733-40
references.pmid: 14680826
references.citation: Biochemistry. 1998 Apr 28;37(17):6124-31
references.pmid: 9558351
references.citation: Nat Rev Mol Cell Biol. 2008 Jul;9(7):532-42
references.pmid: 18568041
references.citation: Nat Chem Biol. 2005 Sep;1(4):223-32
references.pmid: 16408039
references.citation: Biochemistry. 2000 Nov 7;39(44):13584-94
references.pmid: 11063596
references.citation: Biochemistry. 2007 Nov 13;46(45):13199-210
references.pmid: 17956124
references.citation: FEBS Lett. 1989 Mar 27;246(1-2):105-8
references.pmid: 2540029
references.citation: Nature. 2007 Dec 13;450(7172):964-72
references.pmid: 18075575
references.citation: Biochemistry. 1989 Dec 12;28(25):9834-9
references.pmid: 2558730
references.citation: J Mol Biol. 1992 Feb 20;223(4):959-76
references.pmid: 1311391
references.citation: Biochemistry. 2013 Feb 5;52(5):837-46
references.pmid: 23311346
references.citation: Biochemistry. 2011 Nov 22;50(46):10027-40
references.pmid: 22026475
references.citation: Protein Sci. 2009 Jun;18(6):1155-64
references.pmid: 19472325
references.citation: Biochemistry. 2002 Aug 6;41(31):10173-81
references.pmid: 12146983
references.citation: Biochemistry. 2009 Apr 7;48(13):2990-6
references.pmid: 19222214
references.citation: J Biol Inorg Chem. 2000 Aug;5(4):448-54
references.pmid: 10968615
references.citation: Biochemistry. 2005 Feb 22;44(7):2349-59
references.pmid: 15709747
references.citation: Nature. 2009 Dec 3;462(7273):669-73
references.pmid: 19956261
references.citation: Biochemistry. 2002 Jun 18;41(24):7811-8
references.pmid: 12056913
references.citation: J Biol Inorg Chem. 1999 Dec;4(6):717-26
references.pmid: 10631603
references.citation: J Biol Inorg Chem. 2007 Aug;12(6):895-900
references.pmid: 17569996
references.citation: Nature. 2005 Nov 3;438(7064):117-21
references.pmid: 16267559
references.citation: Proteins. 2006 May 1;63(2):349-55
references.pmid: 16287119
references.citation: J Am Chem Soc. 2008 Jun 18;130(24):7540-1
references.pmid: 18494471
references.citation: Biochemistry. 2009 Feb 24;48(7):1613-9
references.pmid: 19183042
references.citation: Biochemistry. 2005 Mar 1;44(8):2900-8
references.pmid: 15723532
references.citation: J Am Chem Soc. 1977 Jul 20;99(15):5158-67
references.pmid: 194940
references.citation: Biochemistry. 2012 Aug 28;51(34):6760-6
references.pmid: 22803508
references.citation: J Am Chem Soc. 2003 Mar 12;125(10):2913-22
references.pmid: 12617658
references.citation: J Am Chem Soc. 2004 Jun 2;126(21):6751-8
references.pmid: 15161303
references.citation: Biochemistry. 1999 Jun 22;38(25):7900-7
references.pmid: 10387031
references.citation: J Biol Chem. 2001 Apr 20;276(16):13034-8
references.pmid: 11112785
references.citation: Chem Rev. 2004 Feb;104(2):651-97
references.pmid: 14871138
references.citation: Inorg Chem. 2000 Jun 26;39(13):2897-905
references.pmid: 11232830
references.citation: Arch Biochem Biophys. 2002 Aug 15;404(2):227-33
references.pmid: 12147260
references.citation: Inorg Chem. 2006 Aug 7;45(16):6338-46
references.pmid: 16878944
references.citation: Proc Natl Acad Sci U S A. 2012 Jan 3;109(1):125-30
references.pmid: 22190488
references.citation: Proc Natl Acad Sci U S A. 1981 Apr;78(4):2258-62
references.pmid: 6264471
references.citation: Biochemistry. 2007 Sep 18;46(37):10643-54
references.pmid: 17713929
references.citation: Biochemistry. 2005 Nov 15;44(45):14956-68
references.pmid: 16274242
references.citation: Biochemistry. 2009 Jul 21;48(28):6585-97
references.pmid: 19594171
references.citation: Dalton Trans. 2012 Jul 14;41(26):8022-30
references.pmid: 22584876
references.citation: J Am Chem Soc. 2012 Nov 14;134(45):18713-23
references.pmid: 23066867
references.citation: Nature. 2007 Dec 6;450(7171):838-44
references.pmid: 18026086