Elucidating the transcriptional and post-translational systems that regulate snake venom assembly and that control autolysis and self-toxicity

点击翻译按钮获取中文摘要

Viper venom consists of a mixture of nature's most tissue-destructive proteins. These enzymes cause rapid and catastrophic cardiovascular collapse in envenomed rodent prey and, in humans, life-threatening bleeding and non-clotting blood. Yet while this lethal toxin cocktail is stored in the snake's venom gland it is somehow controlled so that the snakes' own tissues are unaffected. This extraordinary biological phenomenon is very poorly understood but is clearly central to the successful evolutionary development of venom as a predation and defensive/offensive survival strategy for venomous snakes. The control of viper protein toxicity has been very little studied because the appropriate gene and protein identification technologies have only recently become available. Previously, using basic biochemical techniques we and others have shown that one group of venom enzymes are kept in a quiescent state until activated by other, unknown, venom enzymes in an equally unknown time frame. It is also believed venom contains inhibitors to three key viper venom toxins but this has yet to be experimentally verified. We have recently developed expertise and resources in the application of new high throughput methods to identify new viper venom genes. Here, in the first study of its kind, we aim to provide the first holistic view of how sets of toxin and toxin-regulating venom gland genes are orchestrated during venom synthesis. Assisted by new gene and protein quantification technologies, we will first identify the genes and their protein products that constitute a model viper venom. Next, we will monitor the changes in the levels of these genes and proteins at several intervals spanning the time from when the snake ejects venom to the time it re-synthesises a fully competent arsenal of new venom. Using computational techniques, we will distinguish between toxins and proteins predicted to regulate their toxic activity. We will use molecular techniques to identify whether the genetic machinery controlling the production of (i) the toxins and (ii) the toxin-regulatory proteins, are co-ordinated to ensure that the regulatory proteins are produced before the respective toxin. The results of this study will greatly improve our understanding of the dynamics and the fundamental biological principles regulating venom assembly and venom toxicity.