Venom Diversity and Evolution in the Most Divergent Cone Snail Genus Profundiconus

Abstract

Profundiconus is the most divergent cone snail genus and its unique phylogenetic position, sister to the rest of the family Conidae, makes it a key taxon for examining venom evolution and diversity. Venom gland and foot transcriptomes of Profundiconus cf. vaubani and Profundiconus neocaledonicus were de novo assembled, annotated, and analyzed for differential expression. One hundred and thirty-seven venom components were identified from P. cf. vaubani and 82 from P. neocaledonicus, with only four shared by both species. The majority of the transcript diversity was composed of putative peptides, including conotoxins, profunditoxins, turripeptides, insulin, and prohormone-4. However, there were also a significant percentage of other putative venom components such as chymotrypsin and L-rhamnose-binding lectin. The large majority of conotoxins appeared to be from new gene superfamilies, three of which are highly different from previously reported venom peptide toxins. Their low conotoxin diversity and the type of insulin found suggested that these species, for which no ecological information are available, have a worm or molluscan diet associated with a narrow dietary breadth. Our results indicate that Profundiconus venom is highly distinct from that of other cone snails, and therefore important for examining venom evolution in the Conidae family.

A phylogeny-aware approach reveals unexpected venom components in divergent lineages of cone snails

“…The 98 and 58 transcripts of known gene superfamilies identified for Conasprella and Pygmaeconus , respectively, are well within the diversity range reported in the single-transcriptome studies on Conus . These numbers slightly exceed those reported for P. neocaledonicus (55—[19]), but a much higher diversity is reported for Californiconus (185—[5]). In part, this can be explained by biological factors, such as dietary breadth, varying among taxa, with the most diverse diet found in Californiconus [5].…”

“…The assembly metrics were checked using the TrinityStats.pl module. The same parameters were used to trim and assemble raw read data on Profundiconus neocaledonicus [19], hereafter Profundiconus, and C. californicus [5], hereafter Californiconus (electronic supplementary material, table S1). To quantify the abundance of the predicted transcripts we used the function rsem-calculate-expression [30], with bowtie2 [31] mapper to map the trimmed reads on the assembly.…”

“…This database was obtained by combining all entries with the keyword 'toxin' from UniProt with all entries from ConoServer [32], and supplemented by lists of putative gastropod toxins of the tonnoidean Charonia tritonis [33], buccinoideans Cumia reticulata [34] and Hemifusus tuba [35], non-conid conoideans Clavus canalicularis and C. davidgilmouri [36], and cone snails Profundiconus spp. [19], Conus ermineus [23], Conus magus [37], Conus tribblei [38], Conus praecellens [29], Conus betulinus [39] and Conus litteratus [40] plus the 15 species of Conus and Californiconus, analysed by Phuong et al [5]. Then alignments of the contigs that produced reliable hits (BLAST PID > 0.55, with aligned length no less than half of the best matching database entry, and with no stop codons) were parsed from the XML output by the Python script1 and checked visually.…”

“…Current knowledge of venom composition among these taxa is highly skewed [15]. While a wealth of data is available for Conus species and for the single species of Californiconus, C. californicus [5,16], only fragmentary data has been published for Conasprella [17,18], the first and only analysis of Profundiconus venom was published only recently [19], and virtually no data exist for other divergent Conidae. To fill this gap, we carried out the first comprehensive transcriptomic analyses for Conasprella and Pygmaeconus and we present the results here.…”

An integrated transcriptomic and proteomic approach to identify the main Torymus sinensis venom components

“…An example of this protein is PH-4 (neuropeptide prohormone-4) of Profundiconus cone snail genus. This protein, found also in the venom of other sea snails, has a mature sequence and a precursor-related peptide containing low-density lipoprotein receptor A domain 163 . Another example is PS1 (peptidase S1) from the crustacean Xibalbanus tulumensis, which also contains a low-density lipoprotein receptor A domain.…”