The self-association of the cyclotide kalata B2 in solution is guided by hydrophobic interactions

Rosengren, K. Johan, Daly, Norelle L., Harvey, Peta J. and Craik, David J. (2013) The self-association of the cyclotide kalata B2 in solution is guided by hydrophobic interactions. Peptide Science, Accepted Article 1-16. doi:10.1002/bip.22269

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Author Rosengren, K. Johan
Daly, Norelle L.
Harvey, Peta J.
Craik, David J.
Title The self-association of the cyclotide kalata B2 in solution is guided by hydrophobic interactions
Journal name Peptide Science   Check publisher's open access policy
ISSN 0006-3525
Publication date 2013-07-26
Year available 2013
Sub-type Article (original research)
DOI 10.1002/bip.22269
Volume Accepted Article
Start page 1
End page 16
Total pages 16
Place of publication Hoboken, NJ, United States
Publisher John Wiley & Sons
Collection year 2014
Language eng
Formatted abstract
The cyclotides are a family of small head-to-tail cyclic plant defense proteins. In addition to their cyclic backbone, cyclotides comprise three disulfide bonds in a knotted arrangement, resulting in a highly cross-braced structure that provides exceptional chemical and proteolytic stability. A number of bioactivities have been associated with cyclotides, including insecticidal, antimicrobial, anti-viral and cytotoxic, and these activities are related to an ability to target and disrupt biological membranes. Kalata B2 and to a lesser extent kalata B1, isolated from Oldenlandia affinis, self-associate to tetramers and octamers in aqueous buffers, and this oligomerisation has been suggested to be relevant for their ability to form pores in membranes. Here we demonstrate by solution NMR spectroscopy analysis that the oligomerization of kalata B2 is concentration dependent and that it involves the packing of hydrophobic residues normally exposed on the surface of kalata B2 into a multimeric hydrophobic core. Interestingly, the hydrophobic surface that is “quenched” has previously been shown to be responsible for the ability of kalata B2 to insert into membranes. Thus it seems unlikely that the oligomers observed in aqueous solution are related to any multimeric state present in a membrane environment, and responsible for the formation of pores. The ability to self-associate might alternatively provide a mechanism for preventing self-toxicity when stored at high concentrations in intracellular compartments.
Keyword Cyclic peptides
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Accepted manuscript online: 26 JUL 2013

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Biomedical Sciences Publications
Institute for Molecular Bioscience - Publications
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Citation counts: TR Web of Science Citation Count  Cited 9 times in Thomson Reuters Web of Science Article | Citations
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Created: Tue, 17 Sep 2013, 14:30:08 EST by Susan Allen on behalf of School of Biomedical Sciences