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Mutations in Eukaryotic Translation Elongation Factor 1A that alter Protein Synthesis and Actin Bundling

by
Winder Bienvenido Perez
M.S., Montclair State University - 2009

Thesis advisor: Terri Goss Kinzy, Ph.D.

Graduate Program in Microbiology and Molecular Genetics

Rutgers University
Robert Wood Johnson Medical School
7th Floor, Conference Room 747

Monday, March 31, 2014
12:00 noon


Abstract

Translation is the process by which cells take the genetic information stored within their DNA and turn it into useable parts (proteins) that can perform various types of work. Highly conserved among prokaryotic and eukaryotic organisms, protein synthesis is mediated by the ribosome and a host of trans-acting factors. Eukaryotic translation can be broken down into three phases: initiation, elongation and termination. During elongation, eukaryotic elongation factor 1A (eEF1A) is responsible for delivering aminoacylated-tRNAs to the ribosome. Apart from its canonical function in translation elongation, eEF1A has been implicated in other processes. The most studied alternate function of eEF1A is its interaction with the actin cytoskeleton. As a vital factor of the translational machinery and a mediator of other cellular activities, eEF1A is a crucial regulator of gene expression. Increased levels of eEF1A expression have been correlated with proliferation, oncogenic transformation and cancer, aging and apoptosis. Given its abundance in the cell, it is possible that increased eEF1A levels are linked to these cellular events not just through changes in its canonical function in translation elongation but also its alternative functions.
Amino acid substitutions in eEF1A that reduce its ability to bind and bundle actin in vitro, cause improper actin organization and reduce total translation in vivo in the yeast Saccharomyces cerevisiae. This study was undertaken to characterize the translational defects of these eEF1A actin bundling mutant strains. The strains exhibited increased levels of phosphorylated initiation factor 2 (eIF2), suggesting the involvement of the Gcn2p protein kinase. Regulation of eEF1A by phosphorylation was also studied to obtain a better understanding of the consequences this kind of post-translational modification has on its function.


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