One Enzyme for Two Distinct Metabolisms

描述（由申请人提供）：含硫代谢物在定义健康细胞活性的许多重要过程中发挥重要作用。为了使硫前体分子可用于随后的代谢，以及DNA和RNA代谢和各种蛋白质翻译后修饰，原核和真核细胞已经开发了补救或保留途径。当这些途径受到损害时，会出现许多与健康相关的影响。例如，甲硫氨酸补救途径的破坏或功能降低具有与癌细胞生长和肝硬化相关的后果。此外，该途径的中间体已被证明影响凋亡过程，而这些中间体的类似物是有前途的治疗剂，选择性地破坏疟疾和锥虫寄生虫的生命周期。尽管这些途径的重要性，微生物和高等生物控制其挽救含硫代谢物的能力的策略还没有很好地理解，也没有很好地理解这些代谢物可能产生的各种方式。在这项研究中，总的目标是更好地了解新发现的和广泛传播的新型硫回收途径的机制和调控。基于最近的研究，很明显，不同生物体采取的重要且令人惊讶的策略是采用核酮糖1，5-二磷酸羧化酶/加氧酶（RubisCO）或RubisCO样蛋白（RLP），或RubisCO和RLP两者作为细胞中锚硫补救途径的关键反应。这两种酶催化细胞中含硫代谢物的代谢和补救所需的绝对必要的反应。使用一种模式生物（Rhodocellum rubrum），其适于遗传和生物化学操作，并且采用有氧和生物化学操作。（RLP锚定）和厌氧（RubisCO锚定的）甲硫氨酸/硫补救途径，我们将寻求：（a）阐明硫补救新途径所需的新反应的参与;（B）确定好氧和厌氧途径是如何被差异控制的;以及（c）确定RubisCO的活性位点区域如何调节并能够催化对硫和碳代谢都至关重要的反应。后者的目标提出了一个前所未有的机会，提供新的范式整合蛋白质结构/功能的关系，以关键和不同的生理过程。

DESCRIPTION (provided by applicant): Sulfur-containing metabolites play significant roles in many important processes that define healthy cellular activity. To make sulfur precursor molecules available for subsequent metabolism, and for DNA and RNA metabolism and various protein posttranslational modifications, prokaryotic and eukaryotic cells have developed salvage or sparing pathways. When such pathways become compromised, there are many health-related effects that are noted. For example, disruption or reduced functioning of the methionine salvage pathway has consequences relative to cancer cell growth and liver cirrhosis. In addition, intermediates of this pathway have been shown to influence apoptotic processes, while analogs of these intermediates are promising therapeutic agents that selectively disrupt the life cycle of malarial and trypanosome parasites. Despite the importance of such pathways, the strategies by which microorganisms and higher organisms control their ability to salvage sulfur-containing metabolites is not well understood, nor is there good understanding of the variety of ways in which these metabolites may be produced. In this investigation, the overall goal is to better understand the mechanism and regulation of newly discovered and wide-spread novel sulfur salvage pathways. Based on recent studies, it is apparent that an important and surprising strategy taken by diverse organisms is to employ ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) or the RubisCO-like protein (RLP), or both RubisCO and RLP, as key reactions that anchor sulfur salvage pathways in the cell. Both enzymes catalyze absolutely essential reactions that are needed for the metabolism and salvage of sulfur-containing metabolites in the cell. Using a model organism (Rhodospirillum rubrum) that is amenable to genetic and biochemical manipulation, and employs both aerobic (RLP-anchored) and anaerobic (RubisCO-anchored) methionine/sulfur salvage pathways, we will seek to: (a) elucidate the involvement of novel reactions required for new pathways of sulfur salvage; (b) determine how the aerobic and anaerobic pathways are differentially controlled; and (c) establish how the active site region of RubisCO accommodates and enables catalysis of reactions crucial to both sulfur and carbon metabolism. The latter aim presents an unprecedented opportunity to provide new paradigms for integrating protein structure/function relationships to key and diverse physiological processes.