title: In vivo synthesis of adenylylated bis(5'-nucleosidyl) tetraphosphates (Ap4N) by Escherichia coli aminoacyl-tRNA synthetases.
abstract: The role of aminoacyl-tRNA synthetases in the in vivo synthesis of adenylylated bis(5'-nucleosidyl) tetraphosphates (Ap4N) was studied by measuring the concentration of these nucleotides in Escherichia coli cells overproducing lysyl-, methionyl- phenylalanyl-, or valyl-tRNA synthetase. Overproduction of each aminoacyl-tRNA synthetase (20- to 80-fold) was accompanied by a significant increase in intracellular Ap4N concentration (3- to 14-fold). As expected, non-adenylylated bis(5'-nucleosidyl) tetraphosphate concentration was not changed by synthetase overproduction. It was also verified that overproduction of an inactive methionyl-tRNA synthetase mutant did not modify Ap4N concentration. Ap4N accumulation during heat shock occurred in all strains studied. The increase factor (approximately 50-fold after 1 hr at 48 degrees C) was not changed by overproduction of any of the aminoacyl-tRNA synthetases studied, including that of the heat-inducible form of lysyl-tRNA synthetase from the lysU gene. Together, these results establish that aminoacyl-tRNA synthetases are involved in Ap4N biosynthesis during exponential growth as well as during heat shock.
authors.affiliation: Laboratoire de Biochimie, Unité de Recherche Associée 240 au Centre National de la Recherche Scientifique, Ecole Polytechnique, Palaiseau, France.
authors.forename: A
authors.initials: A
authors.lastname: Brevet
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: F
authors.initials: F
authors.lastname: Lévêque
authors.forename: P
authors.initials: P
authors.lastname: Plateau
authors.forename: S
authors.initials: S
authors.lastname: Blanquet
mesh_terms: D017766:Acid Anhydride Hydrolases; D000227:Adenine Nucleotides; D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D015226:Dinucleoside Phosphates / Q000096:biosynthesis*; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D008718:Methionine-tRNA Ligase / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010957:Plasmids; D015183:Restriction Mapping
chemical_list: D000227:Adenine Nucleotides; D015226:Dinucleoside Phosphates; C020733:diadenosine tetraphosphate; D010744:Phosphoric Monoester Hydrolases; D017766:Acid Anhydride Hydrolases; C020023:bis(5'-nucleosyl)tetraphosphatase (asymmetrical); D000604:Amino Acyl-tRNA Synthetases; D008718:Methionine-tRNA Ligase