Organization of the trmD gene in E.coli K12

Abstract

Transfer RNA from bacteria is made from precursors which are longer than the mature tRNA. Poly- and monocistronic precursors have been identified. Several exo- and endoribonucleases as well as specific tRNA modifying enzymes are involved in the maturation process. tRNA modification is an integrated step in the biosynthesis of tRNA, why the tRNA modifying enzymes can be considered tRNA biosynthetic enzymes. We have initiated a systematic study of the regulation of such enzymes in order to better understand quantitatively the tRNA modification process. All tRNA are methylated in the TΨC-region by the enzyme tRNA (m5U) methyltransferase. The enzyme tRNA (m1G) methyltransferase catalyzes the formation of 1-methylguanosine (m1G) next to the 3’ side of the anticodon in \( {\text{tRNA}}{\frac{1}{1}^{{\text{eu}}}} \) and \( {\text{tRNA}}{\frac{1}{3}^{{\text{eu}}}} \) (Gauss and Sprinzl (1981). We have shown that the synthesis of tRNA (m5U) methyltransferase is regulated in a similar fashion as stable RNA and ribosomal proteins while the regulation of tRNA (m1G) methyltransferase is quite different. The latter enzyme is more regulated as a protein made in low amounts in the cell. Although both enzymes are involved in the biosynthesis of tRNA they are therefore not coordinately regulated (Ny et al., 1980). Cloning of the gene, trmA, which encodes the tRNA (m5U) methyltransferase has facilitated direct studies of the gene control region (Björk et al., this volume). Here we present the gene organization of the trmD geneKeywordsGene OrganizationtRNA ModificationColE1 PlasmidMature tRNASwedish Cancer SocietyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.