Molecular diversity and function of jasmintides from Jasminum sambac

Jasmintides jS1 and jS2 from Jasminum sambac were previously identified as a novel family of cysteine-rich peptides (CRPs) with an unusual disulfide connectivity. However, very little else is known about jasmintides, particularly their molecular diversity and functions. Here, we report the discovery and characterization of a novel suite of jasmintides from J. sambac using transcriptomic, peptidomic, structural and functional tools.

Transcriptomic analysis of leaves, flowers and roots revealed 14 unique jasmintide precursors, all of which possess a three-domain architecture comprising a signal peptide, a pro-domain and a mature jasmintide domain. Peptidomic analysis, using fractionated mixtures of jasmintides and chemical derivatization of cysteine to pseudolysine, trypsin digestion and MS/MS sequencing, revealed an additional 86 jasmintides, some of which were post-translationally modified. NMR analysis showed that jasmintide jS3 has three anti-parallel β-strands with a three-disulfide connectivity of CysI-CysV, CysII-CysIV and CysIII-CysVI, which is similar to jasmintide jS1. Jasmintide jS3 was able to withstand thermal, acidic and enzymatic degradation and, importantly, exhibited antifeedant activity against mealworm Tenebrio molitor.

Together, this study expands the existing library of jasmintides and furthers our understanding of the molecular diversity and cystine framework of CRPs as scaffolds and tools for engineering peptides targeting pests.