Complete nucleotide sequences of cDNAs encoding long chain α-neurotoxins from sea krait, Laticauda semifasciata

Tamiya, Tôru; Ohno, Satoshi; Nishimura, Eisaku; Fujimi, Takahiko J.; Tsuchiya, Takahide

doi:10.1016/s0041-0101(98)00181-0

Cited by 12 publications

(7 citation statements)

References 11 publications

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“…Alternative splicing is consistently observed in the transcription of eukaryotic genes and has also been reported in snake and scorpion venom peptides [48], [49], [50]. Alternative splicing in conotoxins is generally accompanied by a change in the length of the propeptide sequence.…”

Section: Discussionmentioning

confidence: 87%

Molecular Evolution and Diversity of Conus Peptide Toxins, as Revealed by Gene Structure and Intron Sequence Analyses

Wang

Zhou

et al. 2013

PLoS ONE

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Cone snails, which are predatory marine gastropods, produce a cocktail of venoms used for predation, defense and competition. The major venom component, conotoxin, has received significant attention because it is useful in neuroscience research, drug development and molecular diversity studies. In this study, we report the genomic characterization of nine conotoxin gene superfamilies from 18 Conus species and investigate the relationships among conotoxin gene structure, molecular evolution and diversity. The I1, I2, M, O2, O3, P, S, and T superfamily precursors all contain three exons and two introns, while A superfamily members contain two exons and one intron. The introns are conserved within a certain gene superfamily, and also conserved across different Conus species, but divergent among different superfamilies. The intronic sequences contain many simple repeat sequences and regulatory elements that may influence conotoxin gene expression. Furthermore, due to the unique gene structure of conotoxins, the base substitution rates and the number of positively selected sites vary greatly among exons. Many more point mutations and trinucleotide indels were observed in the mature peptide exon than in the other exons. In addition, the first example of alternative splicing in conotoxin genes was found. These results suggest that the diversity of conotoxin genes has been shaped by point mutations and indels, as well as rare gene recombination or alternative splicing events, and that the unique gene structures could have made a contribution to the evolution of conotoxin genes.

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Section: Discussionmentioning

confidence: 87%

Molecular Evolution and Diversity of Conus Peptide Toxins, as Revealed by Gene Structure and Intron Sequence Analyses

Wang

Zhou

et al. 2013

PLoS ONE

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“…Splicing variations: The difference in isoforms of some proteins due to change of segments can be easily explained based on splicing variation [30]. However, unlike these proteins, the segment switching in viperid 3FTx occurs within exon II and exon III.…”

Section: Resultsmentioning

confidence: 99%

Accelerated exchange of exon segments in Viperid three-finger toxin genes (Sistrurus catenatus edwardsii; Desert Massasauga)

et al. 2008

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BackgroundSnake venoms consist primarily of proteins and peptides showing a myriad of potent biological activities which have been shaped by both adaptive and neutral selective forces. Venom proteins are encoded by multigene families that have evolved through a process of gene duplication followed by accelerated evolution in the protein coding region.ResultsHere we report five gene structures of three-finger toxins from a viperid snake, Sistrurus catenatus edwardsii. These toxin genes are structured similarly to elapid and hydrophiid three-finger toxin genes, with two introns and three exons. Both introns and exons show distinct patterns of segmentation, and the insertion/deletion of segments may define their evolutionary history. The segments in introns, when present, are highly similar to their corresponding segments in other members of the gene family. In contrast, some segments in the exons show high similarity, while others are often distinctly different among corresponding regions of the isoforms.ConclusionOrdered, conserved exon structure strongly suggests that segments in corresponding regions in exons have been exchanged with distinctly different ones during the evolution of these genes. Such a "switching" of segments in exons may result in drastically altering the molecular surface topology and charge, and hence the molecular targets of these three-finger toxins. Thus the phenomenon of accelerated segment switch in exons to alter targeting (ASSET) may play an important role in the evolution of three-finger toxins, resulting in a family of toxins with a highly conserved structural fold but widely varying biological activities.

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“…Exon 1 is highly conserved among this family of toxins and appeared to be protected by the longer intron 1 in a manner similar to that proposed for PLA 2 genes [18]. The insertion of a snoRNA fragment in this intron has resulted in a longer intron 1 compared to intron 1 in the erabutoxin gene from sea snake [35]. SnoRNA insertion can also be found in intron 1 of other three‐finger toxins (NTXs and cardiotoxins) in cobra [20,23,36].…”

Section: Discussionmentioning

confidence: 57%

“…The intron–exon splice junctions show the characteristic GT/AG sites of phase 1 introns [37]. The splice sites of both Lntx and Wntx have been found to be similar to the splice site (phase 1 introns) in genes encoding other LNTXs such as α‐Bgtx [38], Pt‐bp [34] and SNTXs such as Ec [35], cobratoxin [39], Sntxs from N. sputatrix [23] and P. textilis [40] and cardiotoxin from N. sputatrix [20].…”

Section: Discussionmentioning

confidence: 99%

Structurally conserved α‐neurotoxin genes encode functionally diverse proteins in the venom of Naja sputatrix¹

et al. 2003

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The structure and organization of the genes encoding the long-chain neurotoxins and four other isoforms of weak neurotoxins in the venom of Naja sputatrix are reported. The genes contained three exons interrupted by two introns, a structure similar to other members of the three-¢nger toxin family. The proteins encoded by these genes, however, show varied af¢nity towards nicotinic acetylcholine receptors. Phylogenetic analysis of these genes showed that the weak neurotoxin gene is con¢ned to a distinct group. We also observe that speci¢c mutations of the gene provide the diversity in function in these toxins while maintaining a common structural sca¡old. This forms the ¢rst report where the molecular basis of evolution of postsynaptic neurotoxins from an ancestral gene can be demonstrated using the same species of snake.

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Complete nucleotide sequences of cDNAs encoding long chain α-neurotoxins from sea krait, Laticauda semifasciata

Cited by 12 publications

References 11 publications

Molecular Evolution and Diversity of Conus Peptide Toxins, as Revealed by Gene Structure and Intron Sequence Analyses

Molecular Evolution and Diversity of Conus Peptide Toxins, as Revealed by Gene Structure and Intron Sequence Analyses

Accelerated exchange of exon segments in Viperid three-finger toxin genes (Sistrurus catenatus edwardsii; Desert Massasauga)

Structurally conserved α‐neurotoxin genes encode functionally diverse proteins in the venom of Naja sputatrix¹

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Complete nucleotide sequences of cDNAs encoding long chain α-neurotoxins from sea krait, Laticauda semifasciata

Cited by 12 publications

References 11 publications

Molecular Evolution and Diversity of Conus Peptide Toxins, as Revealed by Gene Structure and Intron Sequence Analyses

Molecular Evolution and Diversity of Conus Peptide Toxins, as Revealed by Gene Structure and Intron Sequence Analyses

Accelerated exchange of exon segments in Viperid three-finger toxin genes (Sistrurus catenatus edwardsii; Desert Massasauga)

Structurally conserved α‐neurotoxin genes encode functionally diverse proteins in the venom of Naja sputatrix1

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Structurally conserved α‐neurotoxin genes encode functionally diverse proteins in the venom of Naja sputatrix¹