Tropical vibes from Sri Lanka - cyclotides from Viola betonicifolia by transcriptome and mass spectrometry analysis

Cyclotides are an extremely stable class of peptides, ubiquitously distributed in Violaceae. The aim the present study was to investigate presence cyclotides Sri Lankan Violaceae plants, using combined tools transcriptomics and mass spectrometry. New were discovered for first time wild flora Lanka, within Viola betonicifolia, a plant used traditional medicine as antimicrobial. Plant extracts prepared small scale from betonicifolia subjected LC-MS analysis. Subsequent transcriptome de novo sequencing uncovered 25 new (vibe 1–25) three known (varv A/kalata S, viba 17, 11) peptide sequences Möbius bracelet cyclotide subfamilies well hybrid cyclotides. Among transcripts, putative linear acyclotide 4, vibe 10, 11 22) that lack conserved asparagine or aspartic acid vital cyclisation also present. Four endopeptidases (AEPs), VbAEP1-4 found transcriptome, including asparaginyl ligase (PAL), potentially involved backbone cyclisation, showing >93% sequence homology yedoensis ligases, VyPALs. In addition, we identified two protein disulfide isomerases (PDIs), VbPDI1-2, likely oxidative folding, having high (>74%) with previously reported Rubiaceae PDIs. current highlights ubiquity utility transcriptomic analysis their processing enzyme discovery. variability terms loop sizes residues V. showcase structure adaptable scaffold importance combinatorial library, implicated defense.