Combined x-ray and NMR analysis of the stability of the cyclotide cystine knot fold that underpins its insecticidal activity and potential use as a drug scaffold

Wang, C. K., Hu, S. H., Martin, J. L., Sjogren, T, Hajdu, J, Bohlin, L, Claeson, P, Goransson, U, Rosengren, K. J., Tang, J, Tan, N. H. and Craik, D. J. (2009) Combined x-ray and NMR analysis of the stability of the cyclotide cystine knot fold that underpins its insecticidal activity and potential use as a drug scaffold. Journal of Biological Chemistry, 284 16: 10672-10683. doi:10.1074/jbc.M900021200

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Author Wang, C. K.
Hu, S. H.
Martin, J. L.
Sjogren, T
Hajdu, J
Bohlin, L
Claeson, P
Goransson, U
Rosengren, K. J.
Tang, J
Tan, N. H.
Craik, D. J.
Title Combined x-ray and NMR analysis of the stability of the cyclotide cystine knot fold that underpins its insecticidal activity and potential use as a drug scaffold
Journal name Journal of Biological Chemistry   Check publisher's open access policy
ISSN 0021-9258
1083-351X
Publication date 2009-04-17
Year available 2009
Sub-type Article (original research)
DOI 10.1074/jbc.M900021200
Open Access Status File (Publisher version)
Volume 284
Issue 16
Start page 10672
End page 10683
Total pages 12
Editor Herbert Tabor
Place of publication Bethesda MD, U.S.A.
Publisher American Society for Biochemistry & Molecular Biology
Language eng
Subject C1
970106 Expanding Knowledge in the Biological Sciences
060112 Structural Biology (incl. Macromolecular Modelling)
Abstract Cyclotides are a family of plant defense proteins that are highly resistant to adverse chemical, thermal, and enzymatic treatment. Here, we present the first crystal structure of a cyclotide, varv F, from the European field pansy, Viola arvensis, determined at a resolution of 1.8 Å. The solution state NMR structure was also determined and, combined with measurements of biophysical parameters for several cyclotides, provided an insight into the structural features that account for the remarkable stability of the cyclotide family. The x-ray data confirm the cystine knot topology and the circular backbone, and delineate a conserved network of hydrogen bonds that contribute to the stability of the cyclotide fold. The structural role of a highly conserved Glu residue that has been shown to regulate cyclotide function was also determined, verifying its involvement in a stabilizing hydrogen bond network. We also demonstrate that varv F binds to dodecylphosphocholine micelles, defining the binding orientation and showing that its structure remains unchanged upon binding, further demonstrating that the cyclotide fold is rigid. This study provides a biological insight into the mechanism by which cyclotides maintain their native activity in the unfavorable environment of predator insect guts. It also provides a structural basis for explaining how a cluster of residues important for bioactivity may be involved in self-association interactions in membranes. As well as being important for their bioactivity, the structural rigidity of cyclotides makes them very suitable as a stable template for peptide-based drug design.
Keyword ANTI-HIV ACTIVITY
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes First published online February 10, 2009

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2010 Higher Education Research Data Collection
Institute for Molecular Bioscience - Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 62 times in Thomson Reuters Web of Science Article | Citations
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Created: Thu, 03 Sep 2009, 18:18:28 EST by Mr Andrew Martlew on behalf of Institute for Molecular Bioscience