Receptor Sites and Antagonists for Paralytic Neurotoxins

描述(申请人提供)：电压门控钠通道负责脊椎动物神经和肌肉中动作电位的启动和传播。由于其在运动中的重要生理作用，钠通道是麻痹神经毒素的主要靶点，这些神经毒素作用于五个或更多不同的神经毒素受体位置。多肽蝎子毒素的编码基因已经被克隆并在细菌中成功表达，从而产生大量的这种毒素。因此，这些毒素作为多肽构成了实质性的恐怖威胁。此外，表达强效多肽蝎子毒素的细菌或病毒本身就是恐怖威胁，因为感染这些病原体的人类宿主会导致瘫痪。这项工作的中心假设是，可以产生广泛而有效地预防麻风性多肽神经毒素的毒素拮抗剂。这一假设得到了我们目前研究的概念验证的支持，在该研究中，已经产生了第一个蝎子毒素作用的拮抗剂。在这里提出的研究中，我们将确定a-和β-蝎子毒素在钠通道上的受体位置和作用机制，并开发治疗药物来防止它们的毒性作用以及其他来源的机械相关多肽神经毒素的毒性作用。我们的具体目标是：1.Na通道上蝎子毒素受体位点的分子定位。2.α-和β-蝎子毒素活性部位的分子图谱3.蝎子毒素受体部位的三维模型。4.开发新型有效的毒素和小肽拮抗剂。我们在特定目标1到3所做的所有工作都将立即流入针对特定目标4的毒素拮抗剂的设计和开发，并将极大地推动开发新的治疗药物以防止麻痹神经毒素的威胁的努力。这些研究将为了解毒素对钠通道作用的分子机制提供新的见解，并将有助于开发有效的毒素作用拮抗剂。这些进展将对开发反恐药物武器库至关重要，以防止使用这些强大的麻痹神经毒素进行潜在的生物恐怖袭击而导致的疾病和死亡。除了这些反恐方面的重要进展外，这些研究还将揭示钠通道电压感应和激活门控的分子机制，这是理解电兴奋的分子机制的关键一步，也可能成为开发治疗慢性疼痛和神经系统疾病的药物的新途径。

DESCRIPTION (provided by applicant): Voltage-gated Na channels are responsible for initiation and propagation of the action potential in vertebrate nerve and muscle. Because of its essential physiological role in movement, the Na channel is a prime target of paralytic neurotoxins, which act at five or more distinct neurotoxin receptor sites. The genes encoding the polypeptide scorpion toxins have been cloned and successfully expressed in bacteria to produce large amounts of these toxins. Therefore, these toxins constitute a substantial terrorist threat as peptides. Moreover, bacteria or viruses expressing the potent polypeptide scorpion toxins are themselves terrorist threats because infection of human hosts with these agents would result in paralysis. The central hypothesis of the work proposed here is that toxin antagonists can be produced that will protect broadly and effectively against paralytic peptide neurotoxins. This hypothesis is supported by a proof-of-concept from our current research, in which the first antagonist of scorpion toxin action has been produced. In the research proposed here, we will define the receptor sites and mechanisms of action of the a- and ¿-scorpion toxins on Na channels, and we will develop therapeutic agents to prevent their toxic actions as well as the toxic actions of mechanistically related peptide neurotoxins from other sources. Our Specific Aims are: 1. Molecular mapping of the scorpion toxin receptor sites on Na channels. 2. Molecular mapping of the active sites of a- and ¿-scorpion toxins. 3. Three-dimensional models of the scorpion toxin receptor sites. 4. Development of novel and potent toxin and small peptide antagonists. All of our work in Specific Aims 1 through 3 immediately flow into the design and development of toxin antagonists in Specific Aim 4 and will significantly advance the effort to develop novel therapeutic agents to protect against the threat of paralytic neurotoxins. These studies will provide new insights into the molecular mechanisms of toxin action on Na channels and will lead to development of effective antagonists of toxin action. These advances will be of crucial importance to developing an arsenal of counter-terrorism agents to prevent illness and deaths from potential bioterrorist attacks using these potent paralytic neurotoxins. In addition to these important advances for counter-terrorism, these studies will shed new light on the molecular mechanisms of voltage sensing and activation gating of Na channels, an essential step toward understanding the molecular mechanisms of electrical excitability and potentially a novel approach to development of drugs to treat chronic pain and neurological disease.