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In a significant fraction of the Escherichia coli cytosolic proteins, the N-terminal methionine residue incorporated during the translation initiation step is excised. The N-terminal methionine excision is catalyzed by methionyl-aminopeptidase (MAP). Previous studies have suggested that the action of this enzyme could depend mainly on the nature of the(More)
The polymerase chain reaction (PCR) can be used to amplify a DNA fragment with the concomitant creation of numerous mutations provided that one dNTP substrate is in excess over the three others. Advantage was taken of this behavior to systematically mutagenize a 291-bp-long DNA fragment and to define the rules relating the frequencies of each possible bp(More)
Administration of selenium in humans has anticarcinogenic effects. However, the boundary between cancer-protecting and toxic levels of selenium is extremely narrow. The mechanisms of selenium toxicity need to be fully understood. In Saccharomyces cerevisiae, selenite in the millimolar range is well tolerated by cells. Here we show that the lethal dose of(More)
In Escherichia coli, tyrosyl-tRNA synthetase is known to esterify tRNA(Tyr) with tyrosine. Resulting d-Tyr-tRNA(Tyr) can be hydrolyzed by a d-Tyr-tRNA(Tyr) deacylase. By monitoring E. coli growth in liquid medium, we systematically searched for other d-amino acids, the toxicity of which might be exacerbated by the inactivation of the gene encoding(More)
The heterotrimeric factor e/aIF2 plays a central role in eukaryotic/archaeal initiation of translation. By delivering the initiator methionyl-tRNA to the ribosome, e/aIF2 ensures specificity of initiation codon selection. The three subunits of aIF2 from the hyperthermophilic archaeon Pyrococcus abyssi could be overproduced in Escherichia coli. The beta and(More)
Peptidyl-tRNA hydrolase activity from Escherichia coli ensures the recycling of peptidyl-tRNAs produced through abortion of translation. This activity, which is essential for cell viability, is carried out by a monomeric protein of 193 residues. The structure of crystalline peptidyl-tRNA hydrolase could be solved at 1.2 A resolution. It indicates a single(More)
The Saccharomyces cerevisiae YDL219w (DTD1) gene, which codes for an amino acid sequence sharing 34% identity with the Escherichia coli D-Tyr-tRNA(Tyr) deacylase, was cloned, and its product was functionally characterized. Overexpression in the yeast of the DTD1 gene from a multicopy plasmid increased D-Tyr-tRNA(Tyr) deacylase activity in crude extracts by(More)
D-cysteine, a powerful inhibitor of Escherichia coli growth, is decomposed in vitro into pyruvate, H2S, and NH3 by D-cysteine desulfhydrase. To assess the role of this reaction in the adaptation of the bacterium to growth on D-cysteine, the gene of the desulfhydrase was cloned. It corresponds to the open reading frame yedO at 43.03 min on the genetic map of(More)
D-Tyr-tRNATyr deacylase cleaves the ester bond between a tRNA molecule and a D-amino acid. In Escherichia coli, inactivation of the gene (dtd) encoding this deacylase increases the toxicity of several D-amino acids including D-tyrosine, D-tryptophan, and D-aspartic acid. Here, we demonstrate that, in a Deltadtd cell grown in the presence of 2.4 mm(More)
The nucleotide sequence of a 1.26-kb pair DNA fragment containing the structural gene for Escherichia coli initiation factor IF3 has been determined. An open reading frame of 540 nucleotides is found at the position predicted by genetic studies. The amino-acid sequence deduced from the DNA sequence accounts for a molecular weight 20 530. The important(More)