1mii
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(New page: 200px<br /><applet load="1mii" size="450" color="white" frame="true" align="right" spinBox="true" caption="1mii" /> '''SOLUTION STRUCTURE OF ALPHA-CONOTOXIN MII'''...)
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Revision as of 19:19, 20 November 2007
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SOLUTION STRUCTURE OF ALPHA-CONOTOXIN MII
Overview
alpha-Conotoxin MII, a 16-residue polypeptide from the venom of the, piscivorous cone snail Conus magus, is a potent and highly specific, blocker of mammalian neuronal nicotinic acetylcholine receptors composed, of alpha3 beta2 subunits. The role of this receptor type in the modulation, of neurotransmitter release and its relevance to the problems of addiction, and psychosis emphasize the importance of a structural understanding of, the mode of interaction of MII with the alpha3 beta2 interface. Here we, describe the three-dimensional solution structure of MII determined using, 2D 1H NMR spectroscopy. Structural restraints consisting of 376, interproton distances inferred from NOEs and 12 dihedral restraints, derived from spin-spin coupling constants were used as input for simulated, annealing calculations and energy minimization in the program X-PLOR. The, final set of 20 structures is exceptionally well-defined with mean, pairwise rms differences over the whole molecule of 0.07 A for the, backbone atoms and 0.34 A for all heavy atoms. MII adopts a compact, structure incorporating a central segment of alpha-helix and beta-turns at, the N- and C-termini. The molecule is stabilized by two disulfide bonds, which provide cross-links between the N-terminus and both the middle and, C-terminus of the structure. The susceptibility of the structure to, conformational change was examined using several different solvent, conditions. While the global fold of MII remains the same, the structure, is stabilized in a more hydrophobic environment provided by the addition, of acetonitrile or trifluoroethanol to the aqueous solution. The, distribution of amino acid side chains in MII creates distinct hydrophobic, and polar patches on its surface that may be important for the specific, interaction with the alpha3beta2 neuronal nAChR. A comparison of the, structure of MII with other neuronal-specific alpha-conotoxins provides, insights into their mode of interaction with these receptors.
About this Structure
1MII is a Single protein structure of sequence from [1] with NH2 as ligand. Active as Lysozyme, with EC number 3.2.1.17 Full crystallographic information is available from OCA.
Reference
Three-dimensional solution structure of alpha-conotoxin MII by NMR spectroscopy: effects of solution environment on helicity., Hill JM, Oomen CJ, Miranda LP, Bingham JP, Alewood PF, Craik DJ, Biochemistry. 1998 Nov 10;37(45):15621-30. PMID:9843366
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