The RNA Degradosome: Functional Consequences of Enzyme Association on RNA Metabolism

对基因表达的基本理解需要了解从DNA基因组传递信息的信使RNA转录物的生命周期。解释这个生命周期的结束是具有挑战性的，因为多种细胞酶可能通过独立或组合的作用来控制转录物的分解。该项目的总体目标是通过分析大肠杆菌中一种称为“降解体”的多酶RNA降解复合体来确定酶结合对RNA转录物分解的影响。降解体主要是核糖核酸内酶RNase E、核糖核酸外酶PNPase和RNA解旋酶RhlB的集合，加上糖酵解酶烯醇化酶，该酶在RNA代谢中没有已知的作用。完全理解降解体功能的一个主要障碍是确定烯醇化酶在复合体中所起的作用。第一个目的是确定烯醇化酶是否有助于转录物的分解，可能是通过RNA和能量代谢的协调。第二个目的是确定降解体结合对单个组分酶的影响。RhlB将被用作描述解旋酶在底物和蛋白质结合时结构和功能改变的模型。这将确定可能导致链分离机制的构象变化以及RhlB与降解体相互作用的后果。最终目的是通过解释野生型细胞和无法组装降解体的突变细胞之间观察到的表型差异的分子基础，来辨别降解体组装的细胞益处。来自科学领域代表性不足或背景不利群体的学生将作为研究团队的积极成员参与该项目。

Fundamental understanding of gene expression requires knowing the life cycle of messenger RNA transcripts that transmit information from the DNA genome. Explaining the end of this life cycle is challenging because multiple cellular enzymes may govern transcript disassembly through independent or combinatorial actions. The overall project goal is to define consequences of enzyme association on RNA transcript disassembly through analysis of a multi-enzyme RNA degrading complex from E. coli called the "degradosome". Degradosomes are mainly assemblies of endoribonuclease RNase E, exoribonuclease PNPase, and RNA helicase RhlB, plus the glycolytic enzyme enolase, which has no known role in RNA metabolism. A major obstacle to fully understanding degradosome function is defining the role enolase plays in the complex. The first aim is to resolve whether enolase contributes to transcript disassembly, possibly through coordination of RNA and energy metabolism. The second aim is to determine the impact of degradosome association on individual component enzymes. RhlB will be employed as a model to describe structural and functional alterations helicase enzymes can undergo upon substrate and protein binding. This will identify both the conformational changes likely responsible for the strand separation mechanism and the consequences of RhlB interaction with degradosomes. The final aim is to discern cellular benefits of degradosome assembly by explaining the molecular basis for a phenotypic difference observed between wild-type cells and mutant cells unable to assemble degradosomes. Students from groups underrepresented in science, or of disadvantaged background, will participate in the project as active members of the research team.