title: Transient rates of synthesis of five amionacyl-transfer ribonucleic acid synthetases during a shift-up of Escherichia coli.
abstract: The steady-state levels of a number of aminoacyl-transfer ribonucleic acid synthetases are known to be positively correlated with growth rate in Escherichia coli. To describe the regulation of these enzymes during a nutritional shift-up, use was made of the recent identification of polypeptide chains of several synthetases in whole cell lysates resolved by the O'Farrell two-dimensional gel system. A culture growing in acetate minimal medium was shifted to glucose-rich medium and pulse labeled with [3H]leucine and [3H]isoleucine for 30- or 6-s intervals during the 20 min after the shift. After mixing with a uniformly [35S]sulfate-labeled reference culture, the samples were subjected to two-dimensional gel electrophoresis. The 3H/35S ratio in the resolved synthetase polypeptides provided an accurate estimation of their transient rates of synthesis. Five aminoacyl-transfer ribonucleic acid synthetases (those for argnine, glycine, isoleucine, phenylalanine, and valine) exhibited an increase in formation within 30 to 90 s after the shift-up. The magnitude of the increases corresponded to the final steady-state values and were reached within 2 to 3 min. The addition to rifampin revealed that the increase in the differential rate of valyl-transfer ribonucleic acid synthetase formation was the result of increased messenger ribonucleic acid transcription and not of a relaxation of some translation restriction.
mesh_terms: D000085:Acetates / Q000378:metabolism; D000604:Amino Acyl-tRNA Synthetases / Q000096:biosynthesis*; D001126:Arginine-tRNA Ligase / Q000096:biosynthesis; D004926:Escherichia coli / Q000201:enzymology* / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006032:Glycine-tRNA Ligase / Q000096:biosynthesis; D007533:Isoleucine-tRNA Ligase / Q000096:biosynthesis; D010452:Peptide Biosynthesis; D010652:Phenylalanine-tRNA Ligase / Q000096:biosynthesis; D012293:Rifampin / Q000494:pharmacology; D014637:Valine-tRNA Ligase / Q000096:biosynthesis
chemical_list: D000085:Acetates; D000604:Amino Acyl-tRNA Synthetases; D006032:Glycine-tRNA Ligase; D001126:Arginine-tRNA Ligase; D010652:Phenylalanine-tRNA Ligase; D007533:Isoleucine-tRNA Ligase; D014637:Valine-tRNA Ligase; D005947:Glucose; D012293:Rifampin