Khatibi Negin, Huang Yen-Hua, Wang Conan K, Durek Thomas, Gilding Edward K, Craik David J
Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane QLD 4072, Australia.
J Nat Prod. 2025 Jan 24;88(1):24-35. doi: 10.1021/acs.jnatprod.4c00168. Epub 2024 May 15.
Cyclotides are cysteine-rich plant-derived peptides composed of 28-37 amino acids with a head-to-tail cyclic backbone and a knotted arrangement of three conserved disulfide bonds. Their beneficial biophysical properties make them promising molecules for pharmaceutical and agricultural applications. The Violaceae plant family is the major cyclotide-producing family, and to date, every examined plant from this family has been found to contain cyclotides. The presence of cyclotides in was inferred by mass spectroscopy previously, but their sequences and properties had yet to be explored. In this study, the occurrence of cyclotides in this plant was investigated using proteomics and transcriptomics. Twenty cyclotides were identified at the peptide level, including two new members from the bracelet (Vcom1) and Möbius (Vcom2) subfamilies. Structural analysis of these newly identified peptides demonstrated a similar fold compared with cyclotides from the same respective subfamilies. Biological assays of Vcom1 and Vcom2 revealed them to be cytotoxic to Sf9 insect cell lines, with Vcom1 demonstrating higher potency than Vcom2. The results suggest that they could be further explored as insecticidal agents and confirm earlier general findings that bracelet cyclotides have more potent insecticidal activity than their Möbius relatives. Seven new cyclotide-like sequences were observed in the transcriptome of , highlighting the Violaceae as a rich source for new cyclotides with potential insecticidal activity. An analysis of sequences flanking the cyclotide domain in the various precursors from and other Violaceae plants revealed new insights into cyclotide processing and suggested the possibility of two alternative classes of N-terminal processing enzymes for cyclotide biosynthesis.
环肽是富含半胱氨酸的植物源肽，由28 - 37个氨基酸组成，具有头尾相连的环状骨架和三个保守二硫键的扭结排列。它们有益的生物物理特性使其成为制药和农业应用中很有前景的分子。堇菜科植物是主要的环肽产生科，迄今为止，已发现该科每一种被检测的植物都含有环肽。此前通过质谱推断出该植物中环肽的存在，但其序列和特性尚未得到探索探索探索。在本研究中，使用蛋白质组学和转录组学方法研究了该植物中环肽的存在情况。在肽水平上鉴定出20种环肽，包括来自手镯（Vcom1）和莫比乌斯（Vcom2）亚家族的两个新成员。对这些新鉴定肽的结构分析表明，与来自相同亚家族的环肽相比，它们具有相似的折叠结构。Vcom1和Vcom2的生物学测定表明它们对Sf9昆虫细胞系具有细胞毒性，其中Vcom1的活性高于Vcom2。结果表明，它们可作为杀虫剂进一步研究，并证实了早期的一般发现，即手镯型环肽比其莫比乌斯亲属具有更强的杀虫活性。在该植物的转录组中观察到7个新的类环肽序列，突出了堇菜科作为具有潜在杀虫活性的新环肽的丰富来源。对该植物和其他堇菜科植物各种前体中环肽结构域侧翼序列的分析揭示了环肽加工的新见解，并提出了环肽生物合成中两种替代类型的N端加工酶的可能性。
