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

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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.