High conopeptide diversity in Conus striatus: Revealed by integration of two transcriptome sequencing platforms

Abstract

Marine cone snail venoms represent a vast library of bioactive peptides with proven potential as research tools, drug leads, and therapeutics. In this study, a transcriptome library of four different organs, namely radular sheath, venom duct, venom gland, and salivary gland, from piscivorous Conus striatus was constructed and sequenced using both Illumina next-generation sequencing (NGS) and PacBio third-generation sequencing (TGS) technologies. A total of 428 conotoxin precursor peptides were retrieved from these transcriptome data, of which 413 conotoxin sequences assigned to 13 gene superfamilies, and 15 conotoxin sequences were classified as unassigned families. It is worth noting that there were significant differences in the diversity of conotoxins identified from the NGS and TGS data: 82 conotoxins were identified from the NGS datasets while 366 conotoxins from the TGS datasets. Interestingly, we found point mutations in the signal peptide sequences of some conotoxins with the same mature sequence. Therefore, TGS broke the traditional view of the conservation of conotoxin signal peptides and the variability of mature peptides obtained by NGS technology. These results shed light on the integrated NGS and TGS technologies to mine diverse conotoxins in Conus species, which will greatly contribute to the discovery of novel conotoxins and the development of new marine drugs.

Cysteine‐free cone snail venom peptides: Classification of precursor proteins and identification of mature peptides

“…The MLRLI superfamily (Figure 1, sequences 3a-b) aligns with the B2 superfamily, from which multiple linear peptides have been reported from various species. 37,38,40 Related precursor sequences have been reported by Robinson et al…”

“…The MSKLV superfamily (Figure 1, sequence 2) yielded only two related sequences ( C. monile and C. araneosus ) may be classified tentatively as new superfamily‐2 (NSF‐2). The MLRLI superfamily (Figure 1, sequences 3a‐b) aligns with the B2 superfamily, from which multiple linear peptides have been reported from various species 37,38,40 . Related precursor sequences have been reported by Robinson et al from transcriptomic analysis of C. victoriae 40 .…”

“…All the three peptides are post translationally modified by C‐terminus amidation, a characteristic feature of many conopeptides and neuropeptides, involved in cellular signaling in diverse organisms. The availability of partial peptide sequences from the mass spectrometric analysis of venom extracts, permitted us to scan the transcriptome database and identify corresponding precursor protein sequences, which could be then classified into specific gene superfamilies 37,38 . The classification of the precursor protein sequences is presented first followed by the mass spectrometric data, which establishes the presence of multiple cysteine‐free peptides in Conus venoms.…”

Collaborative Expression: Transcriptomics of Conus virgo Suggests Contribution of Multiple Secretory Glands to Venom Production

“…To corroborate the tissue specific patterns of peptide expression inferred from the vermivorous Conus virgo , we accessed VG and SG transcriptomic datasets of five further species: two distantly related fish hunters, Conus geographus (Koch et al 2022 ) and C. striatus (Liao et al 2022 ), a presumed fish hunter C. rolani (Koch et al 2022 ), a mollusk hunter C. episcopatus (Lavergne et al 2015 ), and one more vermivore, C. quercinus (Gao et al 2018 ). For each species, the reads of the two tissues were assembled during a single Trinity run, and BUSCO was used to assess the assembly quality.…”

“…Both these studies support the hypothesis that SG secretion may play some role in envenomation. However, there is currently no studies published to comprehensively characterize the set of genes expressed in the SG and ASG based on RNA-Seq data, even though SG transcriptomic datasets have been published for a few Conus species recently (Gao et al 2018 , Dutertre et al 2014 ; Liao et al 2022 ; Koch et al 2022 ). To fill this gap, in the present study we generated original RNA-Seq data for VG, SG, and ASG of Conus virgo (Fig.…”