Enzymology of H2S Biogenesis

描述（由申请人提供）：内源性产生的H2S是一种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的信号分子，这一发现最近激发了人们对理解其生物学和开发其药理学潜力的极大兴趣。参与硫代谢的酶催化H2S的生物合成，包括：胱硫醚-合酶（CBS）、-胱硫醚酶（CSE）和巯基丙酮酸硫转移酶（MST）。然而，尽管对H2S生物化学的兴趣日益增加，但关于其产生、其作用机制和其破坏的调节仍然存在基本问题。在这项研究中，我们建议通过解决以下具体目标来解决我们对H2S生产的反应机制和调节的理解中的重大差距。(i)H2S生物合成的结构-功能研究将集中于阐明CBS、CSE和MST的反应机制，并使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CBS、CSE和MST通过氧化还原、雄激素和sumoylation的调节，以确定这些参数如何调节H2S的产生、影响细胞周期期间谷胱甘肽池的转硫通量和定位。拟议研究的影响是根本性的（即，获得对H2S生成酶的操作和调节的了解）和翻译（即，为规避代谢阻断提供治疗选择，筛选H2S产生的激活剂/抑制剂，并表征雄激素响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).