title: Both Met(109) and Met(112) are utilized for Cu(II) coordination by the amyloidogenic fragment of the human prion protein at physiological pH.
abstract: The prion protein is a ubiquitous neuronal membrane protein. Misfolding of the prion protein has been implicated in transmissible spongiform encephalopathies (prion diseases). It has been demonstrated that the human prion protein (PrP) is capable of coordinating at least five Cu(II) ions under physiological conditions; four copper binding sites can be found in the octarepeat domain between residues 61 and 91, while another copper binding site can be found in the unstructured "amyloidogenic" domain between residues 91 and 126 PrP(91-126). Herein we expand upon a previous study [J. Shearer, P. Soh, Inorg. Chem. 46 (2007) 710-719] where we demonstrated that the physiologically relevant high affinity Cu(II) coordination site within PrP(91-126) is found between residues 106 and 114. It was shown that Cu(II) is contained within a square planar (N/O)3S coordination environment with one His imidazole ligand (H(111)) and one Met thioether ligand (either M(109) or M(112)). The identity of the Met thioether ligand was not identified in that study. In this study we perform a detailed investigation of the Cu(II) coordination environment within the PrP fragment containing residues 106-114 (PrP(106-114)) involving optical, X-ray absorption, EPR, and fluorescence spectroscopies in conjunction with electronic structure calculations. By using derivatives of PrP(106-114) with systematic Met-->Ile "mutations" we show that the CuII coordination environment within PrP(106-114) is actually comprised of a mixture of two major species; one Cu(II)(N/O)3S center with the M(109) thioether coordinated to CuII and another CuII(N/O)3S center with the M(112) thioether coordinated to CuII. Furthermore, deletion of one or more Met residues from the primary sequence of PrP(106-114) both reduces the CuII affinity of the peptide by two to seven fold, and renders the resulting CuII metallopeptides redox inactive. The biological implications of these findings are discussed.
authors.affiliation: Department of Chemistry/216, University of Nevada, 1664 N. Virginia St. Reno, NV 89503-0216, USA. shearer@unr.edu
authors.forename: Jason
authors.initials: J
authors.lastname: Shearer
authors.forename: Pamela
authors.initials: P
authors.lastname: Soh
authors.forename: Stefanie
authors.initials: S
authors.lastname: Lentz
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D003300:Copper / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D011328:Prions / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
chemical_list: D000682:Amyloid; D010455:Peptides; D011328:Prions; D003300:Copper
references.citation: Biochem J. 2007 Jun 15;404(3):393-402
references.pmid: 17331076
references.citation: Genome Res. 1998 Oct;8(10):1022-37
references.pmid: 9799790
references.citation: Chembiochem. 2003 Dec 5;4(12):1268-84
references.pmid: 14661267
references.citation: Gene. 2004 Oct 27;341:249-53
references.pmid: 15474307
references.citation: J Am Chem Soc. 2005 Apr 20;127(15):5449-62
references.pmid: 15826182
references.citation: Nature. 2004 Aug 26;430(7003):977-9
references.pmid: 15329705
references.citation: Proc Natl Acad Sci U S A. 1998 Nov 10;95(23):13363-83
references.pmid: 9811807
references.citation: Acc Chem Res. 2004 Feb;37(2):79-85
references.pmid: 14967054
references.citation: Proc Natl Acad Sci U S A. 2001 Jul 17;98(15):8531-5
references.pmid: 11438695
references.citation: J Mol Biol. 2005 Mar 11;346(5):1393-407
references.pmid: 15713489
references.citation: Phys Rev A Gen Phys. 1988 Sep 15;38(6):3098-3100
references.pmid: 9900728
references.citation: Science. 2002 Jun 14;296(5575):1991-5
references.pmid: 12065827
references.citation: Proc Natl Acad Sci U S A. 2005 Jan 18;102(3):651-5
references.pmid: 15647366
references.citation: Biochemistry. 2006 Oct 31;45(43):13083-92
references.pmid: 17059225
references.citation: Chem Rev. 2006 Jun;106(6):1995-2044
references.pmid: 16771441
references.citation: Cell. 2005 Apr 22;121(2):195-206
references.pmid: 15851027
references.citation: Inorg Chem. 2005 Oct 3;44(20):7214-25
references.pmid: 16180886
references.citation: J Clin Neurosci. 2001 Sep;8(5):387-97
references.pmid: 11535002
references.citation: Phys Rev B Condens Matter. 1988 Jan 15;37(2):785-789
references.pmid: 9944570
references.citation: Phys Rev B Condens Matter. 1986 Jun 15;33(12):8822-8824
references.pmid: 9938299
references.citation: Inorg Chem. 2006 Dec 11;45(25):10098-107
references.pmid: 17140215
references.citation: Phys Rev A. 1994 Apr;49(4):2421-2431
references.pmid: 9910514
references.citation: Alzheimer Dis Assoc Disord. 2002;16 Suppl 1:S1-8
references.pmid: 12070355
references.citation: Biochemistry. 1998 May 19;37(20):7185-93
references.pmid: 9585530
references.citation: J Biol Inorg Chem. 2006 Sep;11(6):702-11
references.pmid: 16821037
references.citation: Curr Opin Chem Biol. 2003 Feb;7(1):125-35
references.pmid: 12547437
references.citation: J Biol Chem. 2004 Jul 30;279(31):32018-27
references.pmid: 15145944
references.citation: Biochemistry. 2003 Jun 10;42(22):6794-803
references.pmid: 12779334
references.citation: Biochemistry. 2004 Apr 20;43(15):4439-46
references.pmid: 15078089
references.citation: J Mol Biol. 2001 Aug 17;311(3):467-73
references.pmid: 11493001
references.citation: Science. 1997 Oct 10;278(5336):245-51
references.pmid: 9323196
references.citation: Arch Biochem Biophys. 1974 Dec;165(2):691-708
references.pmid: 4374138
references.citation: J Biol Chem. 1998 Dec 11;273(50):33107-10
references.pmid: 9837873
references.citation: Proc Natl Acad Sci U S A. 1999 Dec 21;96(26):15137-42
references.pmid: 10611351
references.citation: Proc Natl Acad Sci U S A. 1999 Mar 2;96(5):2042-7
references.pmid: 10051591
references.citation: Phys Rev B Condens Matter. 1986 Nov 15;34(10):7406
references.pmid: 9949100
references.citation: Chemistry. 2000 Nov 17;6(22):4195-202
references.pmid: 11128284
references.citation: Inorg Chem. 2007 Feb 5;46(3):710-9
references.pmid: 17257012
references.citation: Inorg Chem. 2003 Aug 11;42(16):4790-1
references.pmid: 12895095
references.citation: Nature. 1997 Dec 18-25;390(6661):684-7
references.pmid: 9414160
references.citation: Biochemistry. 2001 Mar 6;40(9):2743-53
references.pmid: 11258885
references.citation: J Biol Chem. 2002 Jun 14;277(24):21140-8
references.pmid: 11912192
references.citation: Science. 1982 Apr 9;216(4542):136-44
references.pmid: 6801762