title: Structure, dynamics, and selectivity of the sodium channel blocker mu-conotoxin SIIIA.
abstract: mu-SIIIA, a novel mu-conotoxin from Conus striatus, appeared to be a selective blocker of tetrodotoxin-resistant sodium channels in frog preparations. It also exhibited potent analgesic activity in mice, although its selectivity profile against mammalian sodium channels remains unknown. We have determined the structure of mu-SIIIA in aqueous solution and characterized its backbone dynamics by NMR and its functional properties electrophysiologically. Consistent with the absence of hydroxyprolines, mu-SIIIA adopts a single conformation with all peptide bonds in the trans conformation. The C-terminal region contains a well-defined helix encompassing residues 11-16, while residues 3-5 in the N-terminal region form a helix-like turn resembling 3 10-helix. The Trp12 and His16 side chains are close together, as in the related conotoxin mu-SmIIIA, but Asn2 is more distant. Dynamics measurements show that the N-terminus and Ser9 have larger-magnitude motions on the subnanosecond time scale, while the C-terminus is more rigid. Cys4, Trp12, and Cys13 undergo significant conformational exchange on microsecond to millisecond time scales. mu-SIIIA is a potent, nearly irreversible blocker of Na V1.2 but also blocks Na V1.4 and Na V1.6 with submicromolar potency. The selectivity profile of mu-SIIIA, including poor activity against the cardiac sodium channel, Na V1.5, is similar to that of the closely related mu-KIIIA, suggesting that the C-terminal regions of both are critical for blocking neuronal Na V1.2. The structural and functional characterization described in this paper of an analgesic mu-conotoxin that targets neuronal subtypes of mammalian sodium channels provides a basis for the design of novel analogues with an improved selectivity profile.
authors.affiliation: Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia.
authors.forename: Shenggen
authors.initials: S
authors.lastname: Yao
authors.forename: Min-Min
authors.initials: MM
authors.lastname: Zhang
authors.forename: Doju
authors.initials: D
authors.lastname: Yoshikami
authors.forename: Layla
authors.initials: L
authors.lastname: Azam
authors.forename: Baldomero M
authors.initials: BM
authors.lastname: Olivera
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Bulaj
authors.forename: Raymond S
authors.initials: RS
authors.lastname: Norton
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D020916:Conotoxins / Q000737:chemistry* / Q000494:pharmacology; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D026941:Sodium Channel Blockers / Q000737:chemistry* / Q000494:pharmacology; D014981:Xenopus
chemical_list: D020916:Conotoxins; D026941:Sodium Channel Blockers
references.citation: Biochemistry. 1996 Jul 9;35(27):8824-35
references.pmid: 8688418
references.citation: J Neurosci. 1998 Jun 15;18(12):4473-81
references.pmid: 9614224
references.citation: Curr Pharm Des. 2000 Aug;6(12):1249-85
references.pmid: 10903392
references.citation: Protein Sci. 1992 Jun;1(6):736-51
references.pmid: 1304915
references.citation: J Biol Chem. 2007 Oct 19;282(42):30699-706
references.pmid: 17724025
references.citation: J Neurosci. 2000 Jan 1;20(1):76-80
references.pmid: 10627583
references.citation: J Mol Biol. 2008 Apr 4;377(4):1216-27
references.pmid: 18295795
references.citation: Biochemistry. 1992 Dec 22;31(50):12577-84
references.pmid: 1335283
references.citation: Neuron. 2000 Apr;26(1):13-25
references.pmid: 10798388
references.citation: J Biol Chem. 2003 Mar 7;278(10):8717-24
references.pmid: 12471026
references.citation: Nucleic Acids Res. 2008 Jan;36(Database issue):D402-8
references.pmid: 17984079
references.citation: J Mol Biol. 1995 Feb 10;246(1):144-63
references.pmid: 7531772
references.citation: J Biomol NMR. 1999 Mar;13(3):289-302
references.pmid: 10212987
references.citation: J Biol Chem. 2002 Jul 26;277(30):27247-55
references.pmid: 12006587
references.citation: Science. 2001 Mar 23;291(5512):2429-33
references.pmid: 11264542
references.citation: Annu Rev Physiol. 2001;63:871-94
references.pmid: 11181979
references.citation: J Comput Aided Mol Des. 2001 Dec;15(12):1119-36
references.pmid: 12160094
references.citation: J Biomol NMR. 1999 Jan;13(1):83-8
references.pmid: 21080267
references.citation: Biochemistry. 1996 Dec 17;35(50):16009-23
references.pmid: 8973171
references.citation: J Mol Graph. 1996 Feb;14(1):51-5, 29-32
references.pmid: 8744573
references.citation: J Biol Chem. 2003 Nov 21;278(47):46805-13
references.pmid: 12970353
references.citation: Protein Sci. 2001 Mar;10(3):538-50
references.pmid: 11344322
references.citation: J Mol Recognit. 2000 Mar-Apr;13(2):55-70
references.pmid: 10822250
references.citation: Annu Rev Biophys Biophys Chem. 1988;17:451-79
references.pmid: 3293595
references.citation: Biochem Pharmacol. 2008 Jun 15;75(12):2334-44
references.pmid: 18486102
references.citation: J Mol Biol. 1993 Nov 20;234(2):405-20
references.pmid: 8230223
references.citation: Biochemistry. 2000 Apr 11;39(14):3908-19
references.pmid: 10747778
references.citation: Biochemistry. 2002 Dec 24;41(51):15388-93
references.pmid: 12484778
references.citation: J Biomol NMR. 1995 Jul;6(1):1-10
references.pmid: 22911575
references.citation: Nature. 1999 Jul 15;400(6741):289-93
references.pmid: 10421374
references.citation: J Biol Chem. 1985 Aug 5;260(16):9280-8
references.pmid: 2410412
references.citation: Proteins. 2007 Apr 1;67(1):18-30
references.pmid: 17256768
references.citation: J Am Chem Soc. 2001 Jun 27;123(25):6118-26
references.pmid: 11414846
references.citation: Chem Biol. 2007 Apr;14(4):399-407
references.pmid: 17462575
references.citation: Biochemistry. 1991 Jul 16;30(28):6908-16
references.pmid: 2069951
references.citation: Curr Opin Struct Biol. 1997 Oct;7(5):732-7
references.pmid: 9345634
references.citation: J Pept Sci. 2007 Apr;13(4):280-5
references.pmid: 17394122
references.citation: Biochemistry. 2005 May 17;44(19):7259-65
references.pmid: 15882064
references.citation: Biochemistry. 2007 Sep 4;46(35):9929-40
references.pmid: 17696362
references.citation: Biochemistry. 1993 Apr 13;32(14):3571-82
references.pmid: 7682109
references.citation: Toxicon. 2006 Dec 1;48(7):780-98
references.pmid: 16952384
references.citation: Biochemistry. 1994 May 17;33(19):5984-6003
references.pmid: 7514039
references.citation: J Biomol NMR. 1996 Dec;8(4):477-86
references.pmid: 9008363
references.citation: J Biol Chem. 1975 Aug 25;250(16):6368-80
references.pmid: 169239
references.citation: Biochimie. 2000 Sep-Oct;82(9-10):883-92
references.pmid: 11086218
references.citation: J Am Chem Soc. 1977 Jan 5;99(1):79-83
references.pmid: 830689
references.citation: Science. 2002 Feb 22;295(5559):1520-3
references.pmid: 11859194
references.citation: Mol Pharmacol. 2007 Mar;71(3):676-85
references.pmid: 17142296
references.citation: J Magn Reson. 2003 Jan;160(1):65-73
references.pmid: 12565051
references.citation: Proc Natl Acad Sci U S A. 1986 Jul;83(14):5321-5
references.pmid: 2425365
references.citation: J Mol Biol. 2002 May 24;319(1):209-27
references.pmid: 12051947