Disease relevance of poxA

• Using a Tn10 insertion greater than 98% cotransduced with the poxA locus, we mapped the poxA gene on the E. coli genetic map [1].
• The crystal structures of Thermus thermophilus lysyl-tRNA synthetase, a class IIb aminoacyl-tRNA synthetase, complexed with Escherchia coli tRNA(Lys)(mnm5 s2UUU) at 2.75 A resolution and with a T. thermophilus tRNA(Lys)(CUU) transcript at 2.9 A resolution are described [2].
• Three Trp variants of lysyl-tRNA synthetase from Bacillus stearothermophilus, in which either one or both of the two Trp residues within the enzyme (Trp314 and Trp332) were substituted by a Phe residue, were produced by site-directed mutagenesis without appreciable loss of catalytic activity [3].
• However, the capacity of tRNA(3)(Lys) to interact with lysyl-tRNA synthetase does not entirely explain the enhanced preference for selection of tRNA(3)(Lys) for the replication of HIV-1 [4].
• The relationship of the pleiotropic phenotypes of the poxA mutants to their SM hypersensitivity is discussed [5].

High impact information on poxA

• Multiple control of Escherichia coli lysyl-tRNA synthetase expression involves a transcriptional repressor and a translational enhancer element [6].
• Searches of the current protein banks also have revealed a high degree of sequence similarity of the lysyl-tRNA synthetase to the product of the Escherichia coli herC gene and to the partial sequence of a protein encoded by an unidentified reading frame located adjacent to the E. coli frdA gene [7].
• In the presence of purified Escherichia coli lysyl-tRNA synthetase [L-lysine:tRNALys ligase (AMP-forming) EC 6.1.1.6], L-lysine, and ATP, addition of the nucleotide ppGpp results in formation of a unique product-A(5')ppp(5') Gpp [8].
• Upon the addition of 3 mM L-leucyl-L-alanine to the medium the lysyl tRNA synthetase activity increases 25-fold and the in vivo charging of lysine tRNA returns to the wild-type level [9].
• To compare amino acid recognition between the two forms of LysRS, the effects of l-lysine analogues on aminoacylation were investigated [10].

Chemical compound and disease context of poxA

• The constitutive lysyl-tRNA synthetase (LysRS) of the Escherichia coli strain OEL134 differs from the wild-type enzyme by the single substitution of threonine 208 with methionine [11].
• Crystals of the thermo-inducible E. coli lysyl-tRNA synthetase LysU which diffract to 2.1 A resolution have been used to determine crystal structures of the enzyme in the presence of lysine, the lysyl-adenylate intermediate, and the nonhydrolyzable ATP analogue AMP-PCP [12].
• During its purification from E. coli K12, lysyl-tRNA synthetase was monitored by its aminoacylation and adenosine(5')tetraphospho(5')adenosine (Ap4A) synthesis activities [13].
• Like the E. coli poxA mutant, this mutant had reduced pyruvate oxidase activity, reduced cross-reacting material to antiserum to purified E. coli pyruvate oxidase, and reduced growth rates [5].
• In addition, the following phenotypes were identified for the E. coli and S. typhimurium poxA mutants: hypersensitivity to SM and alpha-ketobutyrate (AKB), deficiency in AKB metabolism, reduced activity of acetolactate synthase, and hypersensitivity to a wide range of bacterial growth inhibitors, including antibiotics, amino acid analogs, and dyes [5].

Biological context of poxA

• To map this nonselectable mutation, we isolated strains having transposon Tn10 inserted into the chromosome close to the poxA locus and mapped the transposon [1].
• Loss of this base pair reduces mischarging by the E. coli lysyl-tRNA synthetase [14].
• In the present study, the specificity of constitutive lysyl-tRNA synthetase (LysS) from Escherichia coli was analyzed by cross-mutagenesis of the tRNA(Lys) anticodon, on the one hand, and of the amino acid residues composing the anticodon binding site on the other [15].
• A protein domain corresponding to residues 31 to 149 of the E. coli Lysyl-tRNA synthetase species corresponding to the lysS gene was expressed and 15N-labelled [16].
• Therefore, the behavior of the Thr 208 mutants of LysRS supports the idea that the dimerization of class II aminoacyl-tRNA synthetases is important for an efficient structuration of their active site [11].

Anatomical context of poxA

• Lysinoalanine [N epsilon-(DL-2-amino-2-carboxyethyl)-L-lysine; LAL], a nephrotoxic lysine analog, inhibits the lysyl-tRNA-synthetase (EC 6.1.1.6) of prokaryotic and eukaryotic cells competitively at micromolar concentrations [17].

Associations of poxA with chemical compounds

• One of these lesions (designated poxA) decreased the pyruvate oxidase activity to 10 to 15% of the normal level but grew well [1].
• Lysine insertion during coded protein synthesis requires lysyl-tRNA(Lys), which is synthesized by lysyl-tRNA synthetase (LysRS) [10].
• T208A LysRS, in which threonine 208 had been changed into alanine by site-directed mutagenesis, displayed the same properties as T208M LysRS [11].
• The heterogeneity of lysyl-tRNA synthetase (LysRS) was revealed on hydroxyapatite; we focused on the first peak, LysRS1, because of its higher Ap4A/lysyl-tRNA activity ratio at that stage [13].
• The folate operon contains two promoters, one upstream of the first gene and the second preceding LysS [18].

Other interactions of poxA

• In Escherichia coli, two distinct lysyl-tRNA synthetase species are encoded by two genes: the constitutive lysS gene and the thermoinducible lysU gene [19].
• Homology of lysS and lysU, the two Escherichia coli genes encoding distinct lysyl-tRNA synthetase species [19].

Analytical, diagnostic and therapeutic context of poxA

• Upon this transplantation, lysyl-tRNA synthetase loses its capacity to aminoacylate tRNALys [20].
• Crystallization and preliminary diffraction studies of Escherichia coli lysyl-tRNA synthetase (LysU) [21].
• Two-dimensional gel electrophoresis of a whole-cell extract of revertant IH2018 (1.5- to 2-fold wild-type synthetase activity) showed that the increase in synthetase activity is due to the induction of cryptic lysyl-tRNA synthetase forms and not to a change in the constitutive lysyl-tRNA synthetase [22].
• Misacylation of Yeast Amber Suppressor tRNATyr by E. coli Lysyl-tRNA Synthetase and Its Effective Repression by Genetic Engineering of the tRNA Sequence [23].
• Lysyl-tRNA synthetase of Bacillus stearothermophilus molecular cloning and expression of the gene [24].

References