Variations in cyclotide expression in viola species.
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.
Trabi
Manuela
M
Institute for Molecular Bioscience, The University of Queensland, Brisbane QLD 4072, Australia.
Svangård
Erika
E
Herrmann
Anders
A
Göransson
Ulf
U
Claeson
Per
P
Craik
David J
DJ
Bohlin
Lars
L
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*
D047169:Cyclotides; D010456:Peptides, Cyclic; D010940:Plant Proteins; C091930:kalata B1; C473354:varv A; C102384:circulin A