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'''Crystal Structure of Variant 2 Scorpion Toxin from Centruroides sculpturatus Ewing''' | '''Crystal Structure of Variant 2 Scorpion Toxin from Centruroides sculpturatus Ewing''' | ||
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[[Category: Watt, D D.]] | [[Category: Watt, D D.]] | ||
[[Category: Zell, A.]] | [[Category: Zell, A.]] | ||
[[Category: | [[Category: Crystal structure]] | ||
[[Category: | [[Category: Noncrystallographic symmetry]] | ||
[[Category: | [[Category: Scorpion toxin]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 22:06:18 2008'' | |||
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Revision as of 19:06, 2 May 2008
Crystal Structure of Variant 2 Scorpion Toxin from Centruroides sculpturatus Ewing
Overview
Centruroides sculpturatus Ewing variant 2 toxin (CsE-v2) is a neurotoxin isolated from the venom of a scorpion native to the Arizona desert. The structure of CsE-v2 was solved in two different crystal forms using a combination of molecular replacement and multiple isomorphous replacement techniques. Crystals of CsE-v2 display a temperature-dependent, reversible-phase transition near room temperature. At lower temperature the space group changes from P3(2)21 to P3(1)21 with an approximate doubling of the C-axis. The small-cell structure, which has one molecule per asymmetric unit, has an R factor of 0.229 at 2.8 A resolution. The large-cell structure has two molecules per asymmetric unit and was refined at 2.2 A resolution to an R factor of 0.255. CsE-v2 is a rigid, compact structure with four intrachain disulfide bonds. The structure is similar to other long-chain beta neurotoxins, and the largest differences occur in the last six residues. The high-resolution structure of CsE-v2 corrects an error in the reported C-terminal sequence; the terminal tripeptide sequence is Ser 64-Cys 65-Ser 66 rather than Ser 64-Ser 65-Cys 66. Comparison of CsE-v2 with long-chain alpha toxins reveals four insertions and one deletion, as well as additional residues at the N and C termini. Structural alignment of alpha and beta toxins suggests that the primary distinguishing feature between the two classes is the length of the loop between the second and third strands in a three-strand beta sheet. The shorter loop in alpha toxins exposes a critical lysine side chain, whereas the longer loop in beta toxins buries the corresponding basic residue (either arginine or lysine).
About this Structure
1JZB is a Single protein structure of sequence from Centruroides sculpturatus. Full crystallographic information is available from OCA.
Reference
Structure of variant 2 scorpion toxin from Centruroides sculpturatus Ewing., Cook WJ, Zell A, Watt DD, Ealick SE, Protein Sci. 2002 Mar;11(3):479-86. PMID:11847271 Page seeded by OCA on Fri May 2 22:06:18 2008
