Squeezers and leaf-cutters: differential diversification and degeneration of the venom system in toxicoferan reptiles

Fry, Bryan G., Undheim, Eivind A. B., Ali, Syed A., Jackson, Timothy N. W., Debono, Jordan, Scheib, Holger, Ruder, Tim, Morgenstern, David, Cadwallader, Luke, Whitehead, Darryl, Nabuurs, Rob, van der Weerd, Louise, Vidal, Nicolas, Roelants, Kim, Hendrikx, Iwan, Gonzalez, Sandy Pineda, Koludarov, Ivan, Jones, Alun, King, Glenn F., Antunes, Agostinho and Sunagar, Kartik (2013) Squeezers and leaf-cutters: differential diversification and degeneration of the venom system in toxicoferan reptiles. Molecular and Cellular Proteomics, 12 7: 1881-1899. doi:10.1074/mcp.M112.023143

Author Fry, Bryan G.
Undheim, Eivind A. B.
Ali, Syed A.
Jackson, Timothy N. W.
Debono, Jordan
Scheib, Holger
Ruder, Tim
Morgenstern, David
Cadwallader, Luke
Whitehead, Darryl
Nabuurs, Rob
van der Weerd, Louise
Vidal, Nicolas
Roelants, Kim
Hendrikx, Iwan
Gonzalez, Sandy Pineda
Koludarov, Ivan
Jones, Alun
King, Glenn F.
Antunes, Agostinho
Sunagar, Kartik
Title Squeezers and leaf-cutters: differential diversification and degeneration of the venom system in toxicoferan reptiles
Journal name Molecular and Cellular Proteomics   Check publisher's open access policy
ISSN 1535-9476
Publication date 2013-07
Sub-type Article (original research)
DOI 10.1074/mcp.M112.023143
Volume 12
Issue 7
Start page 1881
End page 1899
Total pages 19
Place of publication United States
Publisher American Society for Biochemistry and Molecular Biology
Collection year 2014
Language eng
Formatted abstract
Although it has been established that all toxicoferan squamates share a common venomous ancestor, it has remained unclear whether the maxillary and mandibular venom glands are evolving on separate gene expression trajectories or if they remain under shared genetic control. We show that identical transcripts are simultaneously expressed not only in the mandibular and maxillary glands, but also in the enigmatic snake rictal gland. Toxin molecular frameworks recovered in this study were three-finger toxin (3FTx), CRiSP, crotamine (beta-defensin), cobra venom factor, cystatin, epididymal secretory protein, kunitz, ʟ-amino acid oxidase, lectin, renin aspartate protease, veficolin, and vespryn. We also discovered a novel low-molecular weight disulfide bridged peptide class in pythonid snake glands. In the iguanian lizards, the most highly expressed are potentially antimicrobial in nature (crotamine (beta-defensin) and cystatin), with crotamine (beta-defensin) also the most diverse. However, a number of proteins characterized from anguimorph lizards and caenophidian snakes with hemotoxic or neurotoxic activities were recruited in the common toxicoferan ancestor and remain expressed, albeit in low levels, even in the iguanian lizards. In contrast, the henophidian snakes express 3FTx and lectin toxins as the dominant transcripts. Even in the constricting pythonid and boid snakes, where the glands are predominantly mucous-secreting, low-levels of toxin transcripts can be detected. Venom thus appears to play little role in feeding behavior of most iguanian lizards or the powerful constricting snakes, and the low levels of expression argue against a defensive role. However, clearly the incipient or secondarily atrophied venom systems of these taxa may be a source of novel compounds useful in drug design and discovery.
Keyword Bayesian phylogenetic inference
Cephalic exocrine glands
Gated ion channels
Amino-acid sites
Accelerated evolution
Molecular evolution
Positive selection
Multigene families
Adaptive evolution
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

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