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| {{STRUCTURE_1sn4| PDB=1sn4 | SCENE= }} | | {{STRUCTURE_1sn4| PDB=1sn4 | SCENE= }} |
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| '''STRUCTURE OF SCORPION NEUROTOXIN BMK M4'''
| | ===STRUCTURE OF SCORPION NEUROTOXIN BMK M4=== |
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| ==Overview==
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| The crystal structures of two group III alpha-like toxins from the scorpion Buthus martensii Karsch, BmK M1 and BmK M4, were determined at 1.7 A and 1.3 A resolution and refined to R factors of 0.169 and 0.166, respectively. The first high-resolution structures of the alpha-like scorpion toxin show some striking features compared with structures of the "classical" alpha-toxin. Firstly, a non-proline cis peptide bond between residues 9 and 10 unusually occurs in the five-member reverse turn 8-12. Secondly, the cis peptide 9-10 mediates the spatial relationship between the turn 8-12 and the C-terminal stretch 58-64 through a pair of main-chain hydrogen bonds between residues 10 and 64 to form a unique tertiary arrangement which features the special orientation of the terminal residues 62-64. Finally, in consequence of the peculiar orientation of the C-terminal residues, the functional groups of Arg58, which are crucial for the toxin-receptor interaction, are exposed and accessible in BmK M1 and M4 rather than buried as in the classical alpha-toxins. Sequence alignment and characteristics analysis suggested that the above structural features observed in BmK M1 and M4 occur in all group III alpha-like toxins. Recently, some group III alpha-like toxins were demonstrated to occupy a receptor site different from the classical alpha-toxin. Therefore, the distinct structural features of BmK M1 and M4 presented here may provide the structural basis for the newly recognized toxin-receptor binding site selectivity. Besides, the non-proline cis peptide bonds found in these two structures play a role in the formation of the structural characteristics and in keeping accurate positions of the functionally crucial residues. This manifested a way to achieve high levels of molecular specificity and atomic precision through the strained backbone geometry. | | The line below this paragraph, {{ABSTRACT_PUBMED_10493862}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 10493862 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_10493862}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Scorpion]] | | [[Category: Scorpion]] |
| [[Category: Sodium channel inhibitor]] | | [[Category: Sodium channel inhibitor]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 08:54:43 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 20:54:31 2008'' |
