Determinants of translational efficiency in Saccharomyces cerevisiae

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biology, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references.The goal of this thesis is to elucidate the mechanisms that govern translational efficiency (TE) - the amount of protein produced from each molecule of mRNA. While the mechanisms regulating the TE of a few specific messages are well understood, the general contribution of translational control to differences in cellular protein levels is currently unclear. Recent advances have enabled the direct measurement of protein levels and translation rates genome-wide, and studies in multiple organisms have found varying degrees of translation regulation, both at steady state, and in response to stress or developmental cues. Despite this influx of high-throughput data, the mechanisms underlying the differences in gene-specific and condition-dependent TE remain largely unknown. In this thesis, I describe the roles of two different components of the translational machinery in regulating translational efficiency. In Chapter 1, I discuss the features of mRNA coding sequences that can affect TE, thereby introducing Chapter 2, in which I investigate the role of a conserved anticodon tRNA modification in determining the rate of translation elongation and the phenotypic consequences of its loss for budding yeast. In Chapter 3, I discuss the regulation of translation initiation to introduce Chapter 4, in which I explore how the RNA binding specificity of the core translation factor, yeast eukaryotic initiation factor 4G (eIF4G), contributes to genome-wide competition between mRNAs. Finally, I will discuss future directions for this work.by Boris Zinshteyn.Ph. D