Roles of the two lysyl-tRNA synthetases of Escherichia coli: analysis of nucleotide sequences and mutant behavior.
The complete nucleotide sequence of lysU, the gene for the heat-inducible lysyl-tRNA synthetase of Escherichia coli, was determined and compared with the published sequence of lysS (herC), the gene for the constitutive lysyl-tRNA synthetase. These unlinked genes were found to be identical over 72% of their lengths. The deduced amino acid sequences of the respective gene products, LysU and LysS, were identical over 85% and similar over 92% of their lengths. Accumulation of high levels of LysU during growth of strains carrying the wild-type allele of lysU on multicopy plasmids had no observable effect on growth or on the synthesis of LysS. A lysU deletion strain was constructed and was shown to grow normally at low temperature (28 degrees C) but poorly at 44 degrees C; the slow growth (45% of normal) at elevated temperature was fully reversed by plasmids bearing wild-type lysU. The implications of these findings for the existence of two aminoacyl-tRNA synthetases for lysine are discussed.
Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor 48109-0620.
R L
RL
Clark
F C
FC
Neidhardt
D000595:Amino Acid Sequence; D000604:Amino Acyl-tRNA Synthetases / Q000235:genetics*; D001483:Base Sequence; D002872:Chromosome Deletion; D002874:Chromosome Mapping; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D008250:Lysine-tRNA Ligase / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic
D000604:Amino Acyl-tRNA Synthetases; D008250:Lysine-tRNA Ligase