Why do bacteriophage encode tRNAs?

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This project examines bacteriophage-bacterial interaction systems, surrounding the use of and evolutionary selection for bacteriophage tRNAs. It primarily focuses understanding why bacteriophage encode for tRNAs, and how tRNAs impact bacteriophage host range and bacteriophage virulence. Further routes of investigation will include examining if there is evidence of co-evolution of bacterial hosts and bacteriophage, with respect to observed differences in tRNAs in the host and bacteriophage genomes. Another route of investigation will be to examine if bacteriophage tRNAs and bacterial codons are coding for the same or different tRNAs, and if so, which ones.This project will aim to create a model system using E. coli and T4 bacteriophage. T4 mutants will be created which have each tRNA encoded within T4 systematically knocked out, and these mutants' virulence and host range will be compared against the T4 "wild type" bacteriophage's virulence and host range. Concurrently, this project will undertake bioinformatics and biostatistics research to investigate differences and usage differences in tRNAs within known and sequenced bacteriophage and their hosts. This will involve comparing the phylogenetic evolution of bacteriophage as suggested by whole-genome analysis with the predicted evolution of bacteriophage as suggested by encoded tRNAs. Comparing the evolution based on encoded tRNAs against the tRNAs as encoded by their bacterial hosts will offer insight into whether bacterial tRNAs are regularly and randomly acquired by bacteriophage, if they are highly conserved within bacteriophage genomes from a historic host, or if changes in tRNAs in bacteriophage genomes may be due to random mutation but still under selective evolutionary pressures.