title: Multiple roles of the Cox20 chaperone in assembly of Saccharomyces cerevisiae cytochrome c oxidase.
abstract: The Cox2 subunit of Saccharomyces cerevisiae cytochrome c oxidase is synthesized in the mitochondrial matrix as a precursor whose leader peptide is rapidly processed by the inner membrane protease following translocation to the intermembrane space. Processing is chaperoned by Cox20, an integral inner membrane protein whose hydrophilic domains are located in the intermembrane space, and Cox20 remains associated with mature, unassembled Cox2. The Cox2 C-tail domain is exported post-translationally by the highly conserved translocase Cox18 and associated proteins. We have found that Cox20 is required for efficient export of the Cox2 C-tail. Furthermore, Cox20 interacts by co-immune precipitation with Cox18, and this interaction requires the presence of Cox2. We therefore propose that Cox20 binding to Cox2 on the trans side of the inner membrane accelerates dissociation of newly exported Cox2 from the Cox18 translocase, promoting efficient cycling of the translocase. The requirement for Cox20 in cytochrome c oxidase assembly and respiratory growth is partially bypassed by yme1, mgr1 or mgr3 mutations, each of which reduce i-AAA protease activity in the intermembrane space. Thus, Cox20 also appears to stabilize unassembled Cox2 against degradation by the i-AAA protease. Pre-Cox2 leader peptide processing by Imp1 occurs in the absence of Cox20 and i-AAA protease activity, but is greatly reduced in efficiency. Under these conditions some mature Cox2 is assembled into cytochrome c oxidase allowing weak respiratory growth. Thus, the Cox20 chaperone has important roles in leader peptide processing, C-tail export, and stabilization of Cox2.
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703, USA.
authors.forename: Leah E
authors.initials: LE
authors.lastname: Elliott
authors.forename: Scott A
authors.initials: SA
authors.lastname: Saracco
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Fox
mesh_terms: D003576:Electron Transport Complex IV / Q000737:chemistry / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011485:Protein Binding; D021382:Protein Sorting Signals; D055550:Protein Stability; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C409465:COX18 protein, S cerevisiae; C405324:Cox20 protein, S cerevisiae; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones; D021382:Protein Sorting Signals; D029701:Saccharomyces cerevisiae Proteins; D003576:Electron Transport Complex IV; D010450:Endopeptidases; C067167:IMP1 protein, S cerevisiae
references.citation: Proc Natl Acad Sci U S A. 2010 Mar 16;107(11):5047-52
references.pmid: 20194738
references.citation: J Biol Chem. 2005 Apr 1;280(13):13004-11
references.pmid: 15654078
references.citation: Gene. 2002 Mar 6;286(1):53-63
references.pmid: 11943460
references.citation: J Cell Biol. 2001 May 28;153(5):1085-96
references.pmid: 11381092
references.citation: Proc Natl Acad Sci U S A. 1996 May 28;93(11):5253-7
references.pmid: 8643562
references.citation: Genetics. 1997 Apr;145(4):903-10
references.pmid: 9093845
references.citation: Am J Physiol Cell Physiol. 2006 Dec;291(6):C1129-47
references.pmid: 16760263
references.citation: Proc Natl Acad Sci U S A. 1998 Mar 3;95(5):2250-5
references.pmid: 9482871
references.citation: Mol Biol Cell. 1997 Aug;8(8):1449-60
references.pmid: 9285818
references.citation: Methods Enzymol. 1995;260:224-31
references.pmid: 8592447
references.citation: Biochim Biophys Acta. 2009 Jan;1793(1):60-70
references.pmid: 18522806
references.citation: Mol Gen Genet. 1991 Aug;228(1-2):167-76
references.pmid: 1886606
references.citation: Gene. 2005 Jul 18;354:43-52
references.pmid: 15905047
references.citation: J Biol Chem. 2008 May 30;283(22):15015-22
references.pmid: 18390903
references.citation: Science. 1993 Dec 24;262(5142):1997-2004
references.pmid: 8266095
references.citation: Mol Biol Cell. 2008 Dec;19(12):5387-97
references.pmid: 18843051
references.citation: Mol Cell Biol. 2001 Nov;21(22):7663-72
references.pmid: 11604502
references.citation: Mol Cell Biol. 1995 Aug;15(8):4441-52
references.pmid: 7623837
references.citation: Hoppe Seylers Z Physiol Chem. 1979 Apr;360(4):613-9
references.pmid: 220175
references.citation: J Bacteriol. 1985 Mar;161(3):831-5
references.pmid: 2982789
references.citation: Mol Biol Cell. 1996 Feb;7(2):307-17
references.pmid: 8688560
references.citation: J Biol Chem. 1995 Sep 8;270(36):20879-82
references.pmid: 7673107
references.citation: EMBO J. 1996 Aug 15;15(16):4218-29
references.pmid: 8861950
references.citation: Mol Cell Biol. 2007 Apr;27(7):2476-85
references.pmid: 17261594
references.citation: Mol Biol Cell. 2002 Apr;13(4):1122-31
references.pmid: 11950926
references.citation: Mol Cell Biol. 2007 Jul;27(13):4664-73
references.pmid: 17452441
references.citation: Mol Gen Genet. 2000 Apr;263(3):483-91
references.pmid: 10821182
references.citation: Genetics. 2009 Jun;182(2):519-28
references.pmid: 19307606
references.citation: EMBO J. 1983;2(7):1049-54
references.pmid: 6313350
references.citation: Mol Biol Cell. 2003 Jan;14(1):324-33
references.pmid: 12529447
references.citation: J Biol Chem. 2000 Feb 18;275(7):4571-8
references.pmid: 10671482
references.citation: J Biol Chem. 2001 Mar 2;276(9):6392-7
references.pmid: 11106667
references.citation: Mol Biol Cell. 2004 Apr;15(4):1853-61
references.pmid: 14767059
references.citation: Mol Biol Cell. 2009 Oct;20(20):4371-80
references.pmid: 19710419
references.citation: Yeast. 1995 Oct;11(13):1265-74
references.pmid: 8553697
references.citation: Eukaryot Cell. 2003 Jun;2(3):651-3
references.pmid: 12796311
references.citation: Mol Biol Cell. 2006 Jan;17(1):213-26
references.pmid: 16267274
references.citation: FEMS Yeast Res. 2006 Sep;6(6):869-82
references.pmid: 16911509
references.citation: Science. 1996 May 24;272(5265):1136-44
references.pmid: 8638158
references.citation: Methods Cell Biol. 2001;65:37-51
references.pmid: 11381604
references.citation: Mol Cell Biol. 2001 Apr;21(7):2359-72
references.pmid: 11259585
references.citation: Mol Gen Genet. 2000 Jan;262(6):1036-46
references.pmid: 10660064
references.citation: Mol Cell Biol. 1999 Oct;19(10):6598-607
references.pmid: 10490599
references.citation: Methods Enzymol. 1995;260:213-23
references.pmid: 8592446
references.citation: J Mol Biol. 1982 Apr 25;156(4):683-717
references.pmid: 7120390