Molecular evolution and diversification of snake toxin genes, revealed by analysis of intron sequences

Fujimi, Takahiko J.; Nakajyo, T; Nishimura, Eisaku; Ogura, Eri; Tsuchiya, Takahide; Tamiya, Tôru

doi:10.1016/s0378-1119(03)00637-1

Cited by 34 publications

(25 citation statements)

References 19 publications

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“…2). Similar S/MAR is also found in the first intron of a snake venom neurotoxin LsIII gene [34]. However, there is no significant similarity between the two S/MARs of venom genes.…”

Section: Discussionmentioning

confidence: 58%

“…Thus, all three TSSs are clustered within a compact region and the most frequent TSS is at adenine )112. In contrast, TrFX has five TSSs spread over from )23 to )86 bp (23,32,34,54, and 86 bp upstream of the start codon). The relative abundance of each transcript was one, nine, six, ten and four, respectively, which suggests that the most commonly used TSSs by TrFX gene are the )32 and )54.…”

Section: Transcription Start Sites Of Trocarin D and Trfxmentioning

confidence: 99%

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Structure of two genes encoding parallel prothrombin activators in Tropidechis carinatus snake: gene duplication and recruitment of factor X gene to the venom gland

Reza

Swarup

Kini

2007

Journal of Thrombosis and Haemostasis

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To cite this article: Reza MA, Swarup S, Kini RM. Structure of two genes encoding parallel prothrombin activators in Tropidechis carinatus snake: gene duplication and recruitment of factor X gene to the venom gland J Thromb Haemost 2007; 5: 117-26.Summary. Background: Proteins with new function originate through gene duplication followed by divergence. In nature, occurrence of structurally and functionally similar proteins performing highly diverse physiological roles within an organism is rare. Several Australian elapid snakes have two parallel prothrombin activating systems with distinct physiological roles. For example, in Tropidechis carinatus, trocarin D exists in the venom and acts as toxin, whereas coagulation factor (F) X exists in plasma and plays a role in hemostasis. Results: Here, we show that FX and the trocarin D genes are expressed in a highly tissue-specific manner in T. carinatus. To understand their origin, recruitment and evolution, we determined the complete structure of their genes. Both genes have eight exons with identical exon-intron boundaries. All the introns are 92-99% identical with the exception of intron 1, indicating a recent gene duplication event. The first intron of the trocarin D gene is also nearly identical to that of the FX gene, except for two deletions (255 and 1406 bp) and three insertions (214, 1975, and 2174 bp). The third insertion has a potential scaffold/matrix attached region. The putative promoter of the snake FX gene shares similar cis-elements compared with those of human and murine FX genes. Interestingly, the trocarin D promoter has a 264-bp insertion with core promoter sequences and cis-elements that are known to induce high-level expression. This insertion might be responsible for switching from constitutive expression of the FX gene to inducible expression of trocarin D. Thus, we named this segment as VERSE (Venom Recruitment/Switch Element). Conclusion: To our knowledge, this is the first molecular evidence for the recruitment of a duplicated gene for expression in venom glands by a simple insertion.

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“…2). Similar S/MAR is also found in the first intron of a snake venom neurotoxin LsIII gene [34]. However, there is no significant similarity between the two S/MARs of venom genes.…”

Section: Discussionmentioning

confidence: 58%

Section: Transcription Start Sites Of Trocarin D and Trfxmentioning

confidence: 99%

Structure of two genes encoding parallel prothrombin activators in Tropidechis carinatus snake: gene duplication and recruitment of factor X gene to the venom gland

Reza

Swarup

Kini

2007

Journal of Thrombosis and Haemostasis

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“…Sites under selection in toxin genes may be influenced by a combination of factors, including an animal's feeding habits, their environment and biogeographical factors including population expansions, bottlenecks and vicariance (Juárez et al, 2008). Accelerated rates of evolution in venom gene duplicates have been detected in snake Kunitz-type serine protease inhibitors (Zupunski et al, 2003); snake phospholipase A2s (Kordis and Gubensek, 2000); snake serine proteases (Deshimaru et al, 1996); snake disintegrins, derived from hemorrhagic metalloproteinases (Juárez et al, 2008); snake C-type lectins (Ogawa et al, 2005); snake three-fingered toxins (Fujimi et al, 2003); scorpion sodium channel toxins (Zhu et al, 2004) and cone snail conotoxins (Duda and Palumbi, 1999). Up to 26% of snake disintegrins, which cause profuse bleeding in envenomated victims, are evolving under positive selection.…”

Section: Adaptive Evolution Of Gene Duplicatesmentioning

confidence: 99%

“…The examination of introns in recently duplicated genes is able to shed light on selective pressure, given that intronic regions are normally not functionally conserved (Fujimi et al, 2003). One example involves the identification of diversifying selection acting on snake three-fingered toxins through comparison of relative conservation of intron and exon sequences (Fujimi et al, 2003).…”

Section: Adaptive Evolution Of Gene Duplicatesmentioning

confidence: 99%

“…One example involves the identification of diversifying selection acting on snake three-fingered toxins through comparison of relative conservation of intron and exon sequences (Fujimi et al, 2003). Two groups of three-fingered toxins exist in all elapid snakes: a short form comprising of 60-62 aa and four disulfide bonds, and longer form that ranges from 65 to 74 aa and contains five disulfide bridges.…”

Section: Adaptive Evolution Of Gene Duplicatesmentioning

confidence: 99%

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Venom evolution through gene duplications

Wong

Belov

2012

Gene

116

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Snake venom: From fieldwork to the clinic

et al. 2011

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Snake venoms are recognized here as a grossly under-explored resource in pharmacological prospecting. Discoveries in snake systematics demonstrate that former taxonomic bias in research has led to the neglect of thousands of species of potential medical use. Recent discoveries reveal an unexpectedly vast degree of variation in venom composition among snakes, from different species down to litter mates. The molecular mechanisms underlying this diversity are only beginning to be understood. However, the enormous potential that this resource represents for pharmacological prospecting is clear. New high-throughput screening systems offer greatly increased speed and efficiency in identifying and extracting therapeutically useful molecules. At the same time a global biodiversity crisis is threatening the very snake populations on which hopes for new venom-derived medications depend. Biomedical researchers, pharmacologists, clinicians, herpetologists, and conservation biologists must combine their efforts if the full potential of snake venom-derived medications is to be realized.

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Molecular evolution and diversification of snake toxin genes, revealed by analysis of intron sequences

Cited by 34 publications

References 19 publications

Structure of two genes encoding parallel prothrombin activators in Tropidechis carinatus snake: gene duplication and recruitment of factor X gene to the venom gland

Structure of two genes encoding parallel prothrombin activators in Tropidechis carinatus snake: gene duplication and recruitment of factor X gene to the venom gland

Venom evolution through gene duplications

Snake venom: From fieldwork to the clinic

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