1UG4

Crystal Structure of Cardiotoxin VI from Taiwan Cobra (Naja atra) Venom

Summary for 1UG4

• Entry DOI: 10.2210/pdb1ug4/pdb
• Descriptor: Cytotoxin 6 (2 entities in total)
• Functional Keywords: cardiotoxin, cobra, venom, toxin
• Biological source: Naja atra (Chinese cobra)
• Cellular location: Secreted: P80245
• Total number of polymer chains: 1
• Total formula weight: 6699.20

Authors

Chung, F.-Y.,Wu, W.-G.,Chen, C.-J. (deposition date: 2003-06-12, release date: 2005-02-22, Last modification date: 2023-12-27)

Primary citation

Chen, T.S.,Chung, F.Y.,Tjong, S.C.,Goh, K.S.,Huang, W.N.,Chien, K.Y.,Wu, P.L.,Lin, H.C.,Chen, C.J.,Wu, W.G.
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.
Biochemistry, 44:7414-7426, 2005

PubMed Abstract: 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.

PubMed: 15895985
DOI: 10.1021/bi050172e

Experimental method

X-RAY DIFFRACTION (1.6 Å)