Amino Acid purification and Single-Molecule FRET study of tRNA translocation

Understanding the basic translational mechanisms of the ribosome during protein translation is essential to developing novel chemical defenses against the increasing amount of anti-biotic resistant bacteria. To study the fundamentals of the protein building process, we can employ smFRET studies which require debris-free, pure samples of amino acids, the building blocks of all proteins. Our experiment focused on the overexpression and purification of the Glutamic Acid tRNA and its translocation in the ribosome. This was accomplished by inserting a Glutamic Acid sequence into a vector plasmid through a series of digestion and ligation reactions. The recombinant plasmid was then overexpressed in E. Coli and the tRNA was purified through chloroform extraction, gel filtration, and ion-exchange chromatography. The pure sample was used to make a ribosome complex and the translocation of Glutamic Acid from the A site in the ribosome to the P site was studied through smFRET. From the results, it was concluded that the ribosome can efficiently process the Glutamic Acid tRNA when a frameshifting motif is not present. This raises the question of what may occur if frameshifting motifs are added into an mRNA transcript and how this may affect the trans-locational process of glutamic acid. The future of this study should target the translational process in the presence of frameshifting motifs to identify targets which can halt the building of the proteins. Studies attempting to apply such mechanisms to cells in a host should, however, be mindful that both the bacterial and host ribosomes are susceptible to frameshifting which may limit or complicate discovery of target sites.