Plant cyclotides: A unique family of cyclic and knotted proteins that defines the cyclic cystine knot structural motif

Craik, D. J., Daly, N. L., Bond, T. J. and Waine, C. (1999) Plant cyclotides: A unique family of cyclic and knotted proteins that defines the cyclic cystine knot structural motif. Journal of Molecular Biology, 294 5: 1327-1336. doi:10.1006/jmbi.1999.3383


Author Craik, D. J.
Daly, N. L.
Bond, T. J.
Waine, C.
Title Plant cyclotides: A unique family of cyclic and knotted proteins that defines the cyclic cystine knot structural motif
Journal name Journal of Molecular Biology   Check publisher's open access policy
ISSN 0022-2846
Publication date 1999-01-01
Year available 1999
Sub-type Article (original research)
DOI 10.1006/jmbi.1999.3383
Open Access Status Not yet assessed
Volume 294
Issue 5
Start page 1327
End page 1336
Total pages 10
Place of publication London
Publisher Academic Press
Language eng
Subject C1
670403 Treatments (e.g. chemicals, antibiotics)
250302 Biological and Medical Chemistry
Abstract Several macrocyclic peptides (similar to 30 amino acids), with diverse biological activities, have been isolated from the Rubiaceae and Violaceae plant families over recent years. We have significantly expanded the range of known macrocyclic peptides with the discovery of 16 novel peptides from extracts of Viola hederaceae, Viola odorata and Oldenlandia affinis. The Viola plants had not previously been examined for these peptides and thus represent novel species in which these unusual macrocyclic peptides are produced. Further, we have determined the three-dimensional struc ture of one of these novel peptides, cycloviolacin O1, using H-1 NMR spectroscopy. The structure consists of a distorted triple-stranded beta-sheet and a cystine-knot arrangement of the disulfide bonds. This structure is similar to kalata B1 and circulin A, the only two macrocyclic peptides for which a structure was available, suggesting that despite the sequence variation throughout the peptides they form a family in which the overall fold is conserved. We refer to these peptides as the cyclotide family and their embedded topology as the cyclic cystine knot (CCK) motif. The unique cyclic and knotted nature of these molecules makes them a fascinating example of topologically complex proteins. Examination of the sequences reveals they can be separated into two subfamilies, one of which tends to contain a larger number of positively charged residues and has a bracelet-like circularization of the backbone. The second subfamily contains a backbone twist due to a cis-Pro peptide bond and may conceptually be regarded as a molecular Moebius strip. Here we define the structural features of the two apparent subfamilies of the CCK peptides which may be significant for the likely defense related role of these peptides within plants. (C) 1999 Academic Press.
Keyword Biochemistry & Molecular Biology
Kalata B1
Cyclotides
Nmr Spectroscopy
Cyclic Peptides
Cystine Knot
Growth-factors
Polypeptides
Superfamily
Peptides
Q-Index Code C1
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Institute for Molecular Bioscience - Publications
 
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Created: Mon, 13 Aug 2007, 21:32:09 EST