title: Variations in cyclotide expression in viola species.
abstract: Cyclotides, a family of approximately 50 mini-proteins isolated from various Violaceae and Rubiaceae plants, are characterized by their circular peptide backbone and six conserved cysteine residues arranged in a cystine knot motif. Cyclotides show a wide range of biological activities, making them interesting targets for both pharmaceutical and agrochemical research, but little is known about their natural function and the events that trigger their expression. An investigation of the geographical and seasonal variations of cyclotide profiles has been performed, using the native Australian violet, Viola hederacea, and the Swedish sweet violet, Viola odorata, as model plants. The results showed that in the Australian violet the relative peptide levels of some cyclotides remained almost constant throughout the year, while other cyclotides were present only at certain times of the year. Therefore, it appears that V. hederacea expresses a basic armory of cyclotides as well as special "add-ons" whose levels are influenced by external factors. In the Swedish violet, cyclotide levels were increased up to 14 times during the warmest period of the year. The larger variation in expression levels of the Swedish plants may be a reflection of a greater climatic variation.
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Manuela
authors.initials: M
authors.lastname: Trabi
authors.forename: Erika
authors.initials: E
authors.lastname: Svangård
authors.forename: Anders
authors.initials: A
authors.lastname: Herrmann
authors.forename: Ulf
authors.initials: U
authors.lastname: Göransson
authors.forename: Per
authors.initials: P
authors.lastname: Claeson
authors.forename: David J
authors.initials: DJ
authors.lastname: Craik
authors.forename: Lars
authors.initials: L
authors.lastname: Bohlin
mesh_terms: D000595:Amino Acid Sequence; D002980:Climate; D047169:Cyclotides; D030562:Databases, Protein; D014644:Genetic Variation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000737:chemistry* / Q000235:genetics*; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D013548:Sweden; D032413:Viola / Q000737:chemistry*
chemical_list: D047169:Cyclotides; D010456:Peptides, Cyclic; D010940:Plant Proteins; C091930:kalata B1; C473354:varv A; C102384:circulin A