Peptide name : Cliotide T2 (cT2; Plant defensin)

Source/Organism : Butterfly pea

Linear/Cyclic : Cyclic

Chirality : L

Peptide length: 30

C-terminal modification: Cyclic

N-terminal modification : Not found

Non-natural peptide information: None

Assay type : MTT assay

Assay time : 24h

Activity : IC50 : 8.0 µM

Cell line : HeLa cells

Cancer type : Not found

Other activity : Anti-microbial activity

Amino acid composition bar chart :

Molecular mass : 3285.748 Dalton

Aliphatic index : 0.356

Instability index : 43.1733

Hydrophobicity (GRAVY) : -0.39

Isoelectric point : 4.8704

Charge (pH 7) : -1.2937

Aromaticity : 0.1

Molar extinction coefficient (cysteine, cystine): (6990, 7365)

Hydrophobic/hydrophilic ratio : 1.30769230

hydrophobic moment : -0.135

Missing amino acid : R,H,A,M

Most occurring amino acid : C

Most occurring amino acid frequency : 6

Least occurring amino acid : F

Least occurring amino acid frequency : 1

Secondary structure fraction (Helix, Turn, Sheet): (0.2, 0.3, 0.2)

SMILES Notation: CC[C@H](C)[C@H](NC(=O)[C@@H]1CCCN1C(=O)[C@H](Cc1c[nH]c2ccccc12)NC(=O)[C@H](CC(=O)O)NC(=O)[C@H](CS)NC(=O)[C@H](CO)NC(=O)[C@H](CS)NC(=O)CNC(=O)[C@@H]1CCCN1C(=O)[C@@H](NC(=O)[C@H](Cc1ccc(O)cc1)NC(=O)[C@H](CS)NC(=O)[C@H](CCC(=O)O)NC(=O)CNC(=O)[C@H](CCC(N)=O)NC(=O)[C@@H](NC(=O)[C@H](CS)NC(=O)[C@H](CO)NC(=O)[C@H](CCC(=O)O)NC(=O)CNC(=O)[C@H](CS)NC(=O)[C@H](CCCCN)NC(=O)[C@H](CC(C)C)NC(=O)[C@H](Cc1ccccc1)NC(=O)[C@H](CCC(=O)O)NC(=O)CN)C(C)C)[C@@H](C)O)C(=O)N[C@@H](CS)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CCCCN)C(=O)N[C@@H](CC(N)=O)C(=O)O

1 : Nguyen GK, et al. Discovery and characterization of novel cyclotides originated from chimeric precursors consisting of albumin-1 chain a and cyclotide domains in the Fabaceae family. J Biol Chem. 2011; 286:24275-87. doi: 10.1074/jbc.M111.229922

Paper title : Discovery and characterization of novel cyclotides originated from chimeric precursors consisting of albumin-1 chain a and cyclotide domains in the Fabaceae family.

Doi : https://doi.org/10.1074/jbc.M111.229922

Abstract : The tropical plant Clitoria ternatea is a member of the Fabaceae family well known for its medicinal values. Heat extraction of C. ternatea revealed that the bioactive fractions contained heat-stable cysteine-rich peptides (CRPs). The CRP family of A1b (Albumin-1 chain b/leginsulins), which is a linear cystine knot CRP, has been shown to present abundantly in the Fabaceae. In contrast, the cyclotide family, which also belongs to the cystine knot CRPs but with a cyclic structure, is commonly found in the Rubiaceae, Violaceae, and Cucurbitaceae families. In this study, we report the discovery of a panel of 15 heat-stable CRPs, of which 12 sequences (cliotide T1-T12) are novel. We show unambiguously that the cliotides are cyclotides and not A1bs, as determined by their sequence homology, disulfide connectivity, and membrane active properties indicated by their antimicrobial activities against Escherichia coli and cytotoxicities to HeLa cells. We also show that cliotides are prevalent in C. ternatea and are found in every plant tissue examined, including flowers, seeds, and nodules. In addition, we demonstrate that their precursors are chimeras, half from cyclotide and the other half from Albumin-1, with the cyclotide domain displacing the A1b domain in the precursor. Their chimeric structures likely originate from either horizontal gene transfer or convergent evolution in plant nuclear genomes, which are exceedingly rare events. Such atypical genetic arrangement also implies a different mechanism of biosynthetic processing of cyclotides in the Fabaceae and provides new understanding of their evolution in plants.