UC San Diego

Post-transcriptional regulation represents a powerful and versatile mechanism to fine-tune gene expression to meet cellular and environmental demands. One important aspect of post-transcriptional regulation involves regulation of protein translation, the process of building proteins from a messenger RNA. In this dissertation, I use biochemical and molecular biology techniques to study how translation is mechanistically regulated by both mRNA and protein factors. In chapter 2, I discuss the development of a quantitative method in eukaryotes to measure ribosomal stalls of cis-mRNA factors on protein elongation. We find that different distributions of nonoptimal codons trigger different surveillance and rescue pathways despite similar levels of elongation delay. In chapter 3, I explore the relationship between translatability and mRNA localization during glucose starvation and investigate potential factors that influence this relationship. We find that a complex made from Rvb1 and Rvb2 is involved in promoter-directed cytoplasmic fate in a subset of stress response genes in glucose starvation. Furthermore, we use carefully designed reporters to interrogate how translatability determines cytoplasmic localization and find that active translation is linked to exclusion from stress-induced cytoplasmic granules. Finally in chapter 4, I discuss improvements on the method we have developed, possible future directions for the work described in this dissertation, and my concluding remarks.