Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D03345 (beta-Galactosidase)
 434 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Escherichia coli metY gene, encoding tRNA(f2Met), was split by the kanamycin-resistance-encoding gene. The resulting mutant exhibited the same growth rate as the wild type, indicating that tRNA(f2Met) is not indispensable as is the case with the metZ gene encoding tRNA(f1Met) [Kenri et al., Gene 103 (191) 31-36]. beta-Galactosidase was produced efficiently from the start codon AUG of the intact lacZ gene or a trpA'::lac'Z fusion gene, in the metY mutant. The lac repressor from the lacI gene and the chimeric protein from a hupB'::lac'Z fusion gene, whose start codons are GUG, were also synthesized efficiently in the insertion mutant. These results provide evidence that tRNA(f2Met) is not essential for growth of E. coli and that the start codons, AUG and GUG, are both recognized by tRNA(f1Met), a major N-formyl methionine-specific tRNA, in the tRNA(f2Met)-depleted cells. We were unable to construct mutants deficient in both tRNA(f1Met) and tRNA(f2Met) by P1 phage-mediated transduction with the metY and metZ mutations. Moreover, the ampicillin-resistance marker of the pUC9 plasmid carrying metZ+ was not cured at 42 degrees C in host cells with the polAts and metY-metZ double mutations. These results indicate that either tRNA(f1Met) or tRNA(f2Met) is required for the growth of E. coli.
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PMID:Construction and characterization of an Escherichia coli mutant deficient in the metY gene encoding tRNA(f2Met): either tRNA(f1Met) or tRNA(f2Met) is required for cell growth. 137 81

The Escherichia coli metZ gene encoding tRNA (f1Met) was replaced by the chloramphenicol-resistance-encoding gene. The resulting mutant exhibited slightly lower growth rates as compared to the wild type at 37 degrees C or 42 degrees C, but grew apparently slower than the latter at 30 degrees C, indicating a slight cold sensitivity of growth. beta-Galactosidase was produced efficiently from the start codon AUG of the intact lacZ gene or trpA'::lac' Z fusion gene, in the metZ deletion mutant. The lac repressor from the lacI gene and the chimeric protein from a hupB' ::lac'Z fusion gene, whose start codons are GUG, were also synthesised in the deletion mutant. These results provide evidence that tRNA (f1Met) is not essential for growth of E. coli and that the start codons, AUG and GUG, are both recognized by tRNA (f1Met), a minor N-formyl methionine-specific tRNA, in the tRNA (f1Met)-depleted cells.
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PMID:Construction and characterization of an Escherichia coli mutant with a deletion of the metZ gene encoding tRNA (f1Met). 171 3

An inducible expression system that indirectly regulates gene expression through the use of an inducible suppressor tRNA has been used to express both endogenous and exogenous genes in Dictyostelium. The tetracycline repressor and tRNA suppressor (Glu) are expressed from a single G418 selectable vector, while a gene engineered to contain a stop codon is expressed from a separate hygromycin selectable vector. beta-Galactosidase could be induced over 300 fold with this system, and the extent of induction could be varied depending upon the amount of tetracycline added. It took 3 days to fully induce expression, and about 3 days for expression to decrease to baseline after removal of the tetracycline. Dictyostelium myosin II heavy chain could also be expressed in an inducible manner, although the induction ratio was not as high as beta-galactosidase and the maximum expression level was not as high as wild-type levels. A significant accumulation of the truncated peptide indicates that complete suppression of the stop codon was not achieved. Partial phenotypic reversion was observed in null mutants inducibly expressing myosin II. RacB could also be inducibly expressed, whereas the protein could not be expressed from a constitutive promoter, presumably because expression at high levels is lethal. Therefore, the inducible tRNA system can be used to control expression of endogenous Dictyostelium genes.
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PMID:Regulated expression of myosin II heavy chain and RacB using an inducible tRNA suppressor gene. 1160 56