title: Optimized deep-targeted proteotranscriptomic profiling reveals unexplored Conus toxin diversity and novel cysteine frameworks.
abstract: Cone snails are predatory marine gastropods characterized by a sophisticated venom apparatus responsible for the biosynthesis and delivery of complex mixtures of cysteine-rich toxin peptides. These conotoxins fold into small highly structured frameworks, allowing them to potently and selectively interact with heterologous ion channels and receptors. Approximately 2,000 toxins from an estimated number of >70,000 bioactive peptides have been identified in the genus Conus to date. Here, we describe a high-resolution interrogation of the transcriptomes (available at www.ddbj.nig.ac.jp) and proteomes of the diverse compartments of the Conus episcopatus venom apparatus. Using biochemical and bioinformatic tools, we found the highest number of conopeptides yet discovered in a single Conus specimen, with 3,305 novel precursor toxin sequences classified into 9 known superfamilies (A, I1, I2, M, O1, O2, S, T, Z), and identified 16 new superfamilies showing unique signal peptide signatures. We were also able to depict the largest population of venom peptides containing the pharmacologically active C-C-CC-C-C inhibitor cystine knot and CC-C-C motifs (168 and 44 toxins, respectively), as well as 208 new conotoxins displaying odd numbers of cysteine residues derived from known conotoxin motifs. Importantly, six novel cysteine-rich frameworks were revealed which may have novel pharmacology. Finally, analyses of codon usage bias and RNA-editing processes of the conotoxin transcripts demonstrate a specific conservation of the cysteine skeleton at the nucleic acid level and provide new insights about the origin of sequence hypervariablity in mature toxin regions.
authors.affiliation: Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia;
authors.forename: Vincent
authors.initials: V
authors.lastname: Lavergne
authors.affiliation: Division of Genomics and Computational Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Ivon
authors.initials: I
authors.lastname: Harliwong
authors.affiliation: Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia;
authors.forename: Alun
authors.initials: A
authors.lastname: Jones
authors.affiliation: Division of Genomics and Computational Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Miller
authors.affiliation: Division of Genomics and Computational Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Taft
authors.affiliation: Division of Chemistry and Structural Biology, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia; p.alewood@imb.uq.edu.au.
authors.forename: Paul F
authors.initials: PF
authors.lastname: Alewood
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000825:Animal Structures / Q000378:metabolism; D000818:Animals; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D003062:Codon / Q000235:genetics; D020916:Conotoxins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D052078:Conus Snail / Q000033:anatomy & histology / Q000737:chemistry*; D003545:Cysteine / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D020869:Gene Expression Profiling; D015723:Gene Library; D008969:Molecular Sequence Data; D005810:Multigene Family; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D040901:Proteomics; D012313:RNA / Q000235:genetics / Q000378:metabolism; D017393:RNA Editing; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D003062:Codon; D020916:Conotoxins; D018076:DNA, Complementary; D010455:Peptides; D012313:RNA; D003545:Cysteine
keywords: bioinformatic; conotoxin; cysteine-rich peptides; proteomic; transcriptomic