Characterization of Lysine Transfer Ribonucleic Acid from Vegetative Cells and Spores of Bacillus subtilis

The properties and functions of lysine transfer ribonucleic acid (tRNA) from Bacillus subtilis W23 have been analyzed to determine its possible role in regulation at the translational level of protein synthesis. Two lysine tRNA species were resolved by elution from a benzoylated DEAE-cellulose column. The ratio of these two lysine tRNA's from both vegetative cells and sporulating cells was constant in various media in which the growth rates were quite different. Lysine tRNA1 and lysine tRNA2 responded differently to the lysine codons. The codon AAG was more efficient in binding lysyl-tRNA than the codon AAA in the formation of a lysyl-tRNA-messenger RNA-ribosome complex. Both of the lysine tRNA species were susceptible to iodine oxidation to the same degree, but the amino acid-accepting ability and the binding efficiency to the messenger RNA-ribosome complex of lysine tRNA2 were affected less than those of lysine tRNA1. Spores grown under various nutritional conditions contained only one lysine tRNA peak, which eluted in the position of lysine tRNA1 of vegetative cells. Several possible reasons for the absence of one of the lysine tRNA peaks in spores are discussed. The involvement of lysine tRNA1 and lysine tRNA2 in regulation at the translational level is postulated.