Genetic Dissection of Synthesis and Function of Modified Nucleosides in Bacterial Transfer RNA

Abstract

Publisher Summary This chapter discusses the transfer ribonucleic acid (tRNA) modification-deficient mutants that have been pivotal in unraveling their role in tRNA function. Unexpectedly, some modified nucleosides (m5U54, s4U8, and Q34), which occur frequently in tRNA, show no apparent functional impact on the tRNA based on the normal growth rate of the corresponding mutants. Other modified nucleosides (ms2ioGA37, mlG37, and W38, 39, 40) influence the function of the tRNA, and result in a reduced growth rate and polypeptide chain elongation rate for the mutant. Although, tRNA from all the three phylogenetic domains, archaea, bacteria, and eucarya, earlier called the kingdoms of archaebacteria, eubacteria, and eukaryotes, respectively contains modified nucleosides. A subset of these modified nucleosides is present in the tRNAs from all organisms. Moreover, some are even present in comparable positions in the tRNAs from all three domains. Therefore, the modified nucleosides may have been present in the tRNA of the progenitor. However, some modified nucleosides are domain-specific demonstrating that the presence of these modified nucleosides has evolved after the three phylogenetic domains had separated.