1ug4
Crystal Structure of Cardiotoxin VI from Taiwan Cobra (Naja atra) Venom
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OverviewOverview
Natural homologues of cobra cardiotoxins (CTXs) were classified into two, structural subclasses of group I and II based on the amino acid sequence, and circular dichroism analysis, but the exact differences in their, three-dimensional structures and biological significance remain elusive., We show by circular dichroism, NMR spectroscopic, and X-ray, crystallographic analyses of a newly purified group I CTX A6 from eastern, Taiwan cobra (Naja atra) venoms that its loop I conformation adopts a type, VIa turn with a cis peptide bond located between two proline residues of, PPxY. A similar "banana-twisted" conformation can be observed in other, group I CTXs and also in cyclolinopeptide A and its analogues. By binding, to the membrane environment, group I CTX undergoes a conformational change, to adopt a more extended hydrophobic domain with beta-sheet twisting, closer to the one adopted by group II CTX. This result resolves a, discrepancy in the CTX structural difference reported previously between, solution as well as crystal state and shows that, in addition to the, hydrophobicity, the exact loop I conformation also plays an important role, in CTX-membrane interaction. Potential protein targets of group I CTXs, after cell internalization are also discussed on the basis of the, determined loop I conformation.
About this StructureAbout this Structure
1UG4 is a Single protein structure of sequence from Naja atra. Full crystallographic information is available from OCA.
ReferenceReference
Structural difference between group I and group II cobra cardiotoxins: X-ray, NMR, and CD analysis of the effect of cis-proline conformation on three-fingered toxins., Chen TS, Chung FY, Tjong SC, Goh KS, Huang WN, Chien KY, Wu PL, Lin HC, Chen CJ, Wu WG, Biochemistry. 2005 May 24;44(20):7414-26. PMID:15895985
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