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，钠通道是麻痹性神经毒素的主要靶点，它作用于五个或更多不同的神经毒素受体位点。编码多肽蝎毒素的基因已被克隆并成功地在细菌中表达，从而产生大量的蝎毒素。因此，这些毒素作为多肽构成了巨大的恐怖威胁。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，因为这些病原体感染人类宿主会导致瘫痪。这里提出的工作的中心假设是，毒素拮抗剂可以产生，将保护广泛和有效地对抗麻痹肽神经毒素。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，蝎子毒素作用的第一个拮抗剂已经产生。在这里提出的研究中，我们将确定a-和¿-蝎毒素在Na通道上的受体位点和作用机制，我们将开发治疗药物来阻止它们的毒性作用，以及来自其他来源的机制相关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. 蝎和蝎毒素活性位点的分子作图。3. 蝎子毒素受体部位的三维模型。4. 新型强效毒素和小肽拮抗剂的研制。我们在Specific Aim 1到3中的所有工作都直接流入了Specific Aim 4中毒素拮抗剂的设计和开发，并将显著推进开发新型治疗药物以保护免受麻痹性神经毒素威胁的努力。这些研究将为毒素作用于钠通道的分子机制提供新的见解，并将导致毒素作用的有效拮抗剂的开发。这些进展对于发展反恐制剂武器库至关重要，以防止使用这些强效麻痹性神经毒素的潜在生物恐怖袭击造成的疾病和死亡。除了反恐方面的这些重要进展外，这些研究还将揭示电压传感和Na通道激活门控的分子机制，这是理解电兴奋性分子机制的重要一步，并可能为开发治疗慢性疼痛和神经系统疾病的药物提供新途径。

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.