Characterizing circular peptides in mixtures: sequence fragment assembly of cyclotides from a violet plant by MALDI-TOF/TOF mass spectrometry

Hashempour, Hossein, Koehbach, Johannes, Daly, Norelle L., Ghassempour, Alireza and Gruber, Christian W. (2013) Characterizing circular peptides in mixtures: sequence fragment assembly of cyclotides from a violet plant by MALDI-TOF/TOF mass spectrometry. Amino Acids, 44 2: 581-595. doi:10.1007/s00726-012-1376-x


Author Hashempour, Hossein
Koehbach, Johannes
Daly, Norelle L.
Ghassempour, Alireza
Gruber, Christian W.
Title Characterizing circular peptides in mixtures: sequence fragment assembly of cyclotides from a violet plant by MALDI-TOF/TOF mass spectrometry
Journal name Amino Acids   Check publisher's open access policy
ISSN 0939-4451
1438-2199
Publication date 2013-02-01
Year available 2012
Sub-type Article (original research)
DOI 10.1007/s00726-012-1376-x
Open Access Status DOI
Volume 44
Issue 2
Start page 581
End page 595
Total pages 15
Place of publication Wien, Austria
Publisher Springer Wien
Language eng
Abstract Cyclotides are a very abundant class of plant peptides that display significant sequence variability around a conserved cystine-knot motif and a head-to-tail cyclized backbone conferring them with remarkable stability. Their intrinsic bioactivities combined with tools of peptide engineering make cyclotides an interesting template for the design of novel agrochemicals and pharmaceuticals. However, laborious isolation and purification prior to de novo sequencing limits their discovery and hence their use as scaffolds for peptide-based drug development. Here we extend the knowledge about their sequence diversity by analysing the cyclotide content of a violet species native to Western Asia and the Caucasus region. Using an experimental approach, which was named sequence fragment assembly by MALDI-TOF/TOF, it was possible to characterize 13 cyclotides from Viola ignobilis, whereof ten (vigno 1-10) display previously unknown sequences. Amino acid sequencing of various enzymatic digests of cyclotides allowed the accurate assembly and alignment of smaller fragments to elucidate their primary structure, even when analysing mixtures containing multiple peptides. As a model to further dissect the combinatorial nature of the cyclotide scaffold, we employed in vitro oxidative refolding of representative vigno cyclotides and confirmed the high dependency of folding yield on the inter-cysteine loop sequences. Overall this work highlights the immense structural diversity and plasticity of the unique cyclotide framework. The presented approach for the sequence analysis of peptide mixtures facilitates and accelerates the discovery of novel plant cyclotides.
Keyword Viola ignobilis
Circular
Cystine-knot
Oxidative folding
Vigno
Peptidomics
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID P22889-B11
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biological Sciences Publications
 
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Created: Mon, 13 Nov 2017, 12:38:46 EST