Enzymology of H2S Biogenesis

描述（由申请人提供）：内源性产生的H2S是一种信号分子，在哺乳动物中介导从神经调节到心脏保护的各种生理作用，这一发现激发了人们对其生物学和药理潜力的巨大兴趣。参与硫代谢的酶催化H2S的生物生成，包括：半胱硫氨酸合成酶（CBS）、-半胱硫氨酸酶（CSE）和巯基丙酮酸硫转移酶（MST）。然而，尽管人们对H2S生物化学的兴趣日益浓厚，但关于H2S的产生、作用机制和破坏的调控仍存在一些基本问题。在本研究中，我们建议通过解决以下具体目标来解决我们对H2S产生的反应机制和调控的理解中的重大空白。(i) H2S生物发生的结构-功能研究将重点阐明CBS、CSE和MST的反应机制，并利用小分子文库作为体外和离体筛选CBS和CSE的激活剂和/或抑制剂的平台进行高通量筛选。（ii）将研究氧化还原、雄激素和summoylation对CBS、CSE和MST的调节，以确定这些参数如何调节H2S的产生，影响细胞周期中转硫通量和谷胱甘肽池的定位。拟议研究的影响既有基础的（即，深入了解H2S生成酶的运作和调节），也有翻译的（即，为规避代谢阻断的治疗方案提供信息，筛选H2S生成的激活剂/抑制剂，并表征雄激素反应性前列腺癌中转硫途径的睾酮调节）。

DESCRIPTION (provided by applicant): The discovery that endogenously produced H2S is a signaling molecule that mediates varied physiological effects in mammals ranging from neuromodulatory to cardioprotective, has spurred enormous recent interest in understanding its biology and in exploiting its pharmacological potential. Enzymes involved in sulfur metabolism catalyze the biogenesis of H2S and include: cystathionine -synthase (CBS), - cystathionase (CSE) and mercaptopyruvate sulfurtransferase (MST). However, despite the rising interest in H2S biochemistry, fundamental questions remain regarding regulation of its production, its mechanism of action and its destruction. In this study, we propose to address significant gaps in our understanding of the reaction mechanisms and regulation of H2S production by addressing the following specific aims. (i) Structure- function studies on H2S biogenesis will focus on elucidating the reaction mechanisms of CBS, CSE and MST and conducting a high throughput screen using a small molecule library as a platform for in vitro and ex vivo screening of activators and/or inhibitors of CBS and CSE. (ii) Regulation of CBS, CSE and MST by redox, androgens and sumoylation will be investigated to determine how these parameters modulate H2S production, affect transsulfuration flux and localization of glutathione pools during the cell cycle. The impact of the proposed studies is both fundamental (i.e., gaining insights into the operation and regulation of H2S-generating enzymes) and translational (i.e., informing therapeutic options for circumventing metabolic blockades, screening for activators/inhibitors of H2S production and characterizing testosterone regulation of the transsulfuration pathway in androgen-responsive prostate cancer).