RUI: The Synthesis and Degradation of a Unique Bacterial Polymer

9728609 Allen这项研究的目的是利用多学科方法研究唯一一种已知的非蛋白质聚合物的合成和降解，该方法涉及三名化学、生物化学和生物科学专业的教员和本科生。用15个N标记氮源标记蓝藻后，通过酶分析和纯化以及体内和体外核磁共振波谱研究蓝藻素(多L精氨基多聚L天冬氨酸)的代谢。将研究正常生长期间和在不同营养胁迫条件下的生长期间的氮代谢。将设计实验以确定蓝藻素在蓝藻新陈代谢中是否具有动态作用。蓝藻素是唯一已知的非蛋白质聚合物，其功能是储存氮。虽然它在营养胁迫和固氮过程中大量积累，但对其合成和降解机制知之甚少。当蓝藻缺乏氮时，它就会被动员起来。如果蓝藻素是氮流入代谢池的必需中间体，那么它在蓝藻新陈代谢中的作用将是中心的。因此，重要的是要了解调节策略以及存储如何与中间代谢相结合。这些研究还将有助于确定常量营养素限制和应激如何改变细胞内的代谢通量。当氮素可用时积累并在以后使用的策略必须为采用该策略的有机体提供重要的选择优势。对特定环境反应机制的研究将为基因调控和从环境信号感知到酶活性调控的途径提供新的信息。

9728609 Allen The objective of the research is to study the synthesis and degradation of the only known nonprotein polymer whose function is the storage of nitrogen, using a multidisciplinary approach involving three faculty members and undergraduate women students in chemistry, biological chemistry and biological sciences. The metabolism of cyanophycin (multi-L-arginyl poly L-aspartic acid ) will be investigated by enzyme analysis and purification and by in vivo and in vitro NMR spectroscopy after labeling cyanobacteria with 15 N-labeled nitrogen sources. Nitrogen metabolism will be studied during normal growth and during growth under various conditions of nutrient stress. Experiments will be designed to determine whether cyanophycin has a dynamic role in cyanobacterial metabolism. Cyanophycin is the only known nonprotein polymer whose function is the storage of nitrogen. Little is known about mechanisms of its synthesis and degradation although it accumulates in large amounts during nutrient stress and during nitrogen fixation. It is mobilized when cyanobacteria are starved for nitrogen. If cyanophycin is an obligatory intermediate in the flow of nitrogen into the metabolic pool, its role in cyanobacterial metabolism will be central. It is therefore important to understand regulatory strategies and how storage is integrated with intermediary metabolism. These studies will also help define how macronutrient limitation and stress alter metabolic fluxes in cells. The strategy of accumulating nitrogen when it is available and using it later must impart an important selective advantage to the organism employing that strategy. Studies of the mechanisms involved in specific environmental responses will provide new information about gene regulation and pathways leading from the sensing of environmental signals to the regulation of enzymatic activities.