In vitro mutagenesis of the mitochondrial leucyl-tRNA synthetase of S. cerevisiae reveals residues critical for its in vivo activities.
The mitochondrial leucyl-tRNA synthetase (mLRS) of Saccharomyces cerevisiae is involved in both mitochondrial protein synthesis and pre-mRNA splicing. We have created mutations in the regions HIGH, GWD and KMSKS, which are involved in ATP-, amino acid- and tRNA-binding respectively, and which have been conserved in the evolution of group I tRNA synthetases. The mutants GRD and NMSKS have no discernible phenotype. The mutants AWD and ARD act as null alleles and lead to the production of 100% cytoplasmic petites. The mutants HIGN, NIGH and KMSNS are unable to grow on glycerol even in the presence of an intronless mitochondrial genome and accumulate petites to a greater extent than the wild-type but less than 40%. Experiments with an imported bI4 maturase indicate that the lesion in these mutations primarily affects the synthetase and not the splicing functions.
Li
G Y
GY
Centre de Génétique Moléculaire du C.N.R.S., Université Pierre et Marie Curie, Gif-sur-Yvette, France.
Herbert
C J
CJ
Labouesse
M
M
Slonimski
P P
PP
D001483:Base Sequence; D015152:Blotting, Northern; D004591:Electrophoresis, Polyacrylamide Gel; D007438:Introns; D007935:Leucine-tRNA Ligase / Q000235:genetics*; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
D012333:RNA, Messenger; D007935:Leucine-tRNA Ligase