title: DNA-directed in vitro synthesis of beta-galactosidase. Studies with purified factors.
abstract: The phage DNA-directed synthesis of beta-galactosidase has been examined in a system containing the following purified Escherichia coli factors: RNA polymerase; cyclic AMP receptor protein; N10-formyltetrahydrofolate Met-tRNAf transformylase; initiation factors 1, 2, and 3; elongation factors Tu, Ts, and G; release factors 1 and 2; 20 aminoacyl-tRNA synthetases; L factor (Kung, H. F., Spears, C., and Weissbach, H. (1974) J. Biol. Chem. 250, 1556-1562); and Lalpha (Kung, H.-F., Spears, C., and Weissbach, H. (1976) Fed. proc. 35, 1537). Under these conditions, beta-galactosidase synthesis occurs at less than 1% of the rate obtained with unfractionated extracts, which suggested that other required components were lacking. The difficulty in obtaining large amounts of the purified aminoacyl-tRNA synthetases for these studies made it necessary to modify the system. It was possible to conserve many of the purified aminoacyl-tRNA synthetases since at least 13 of them could be replaced by an Ehrlich ascites extract. The ascites extract plus other E. coli purified factors was used as a basic system to search for additional components required for beta-galactosidase synthesis. The present report describes the purification from E. coli extracts of three fractions, called Lbeta, Lgamma, and Ldelta, that are needed to restore enzyme synthesis.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism; D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism*; D005696:Galactosidases / Q000096:biosynthesis*; D010445:Peptide Elongation Factors
chemical_list: D004279:DNA, Viral; D010445:Peptide Elongation Factors; D005696:Galactosidases; D000604:Amino Acyl-tRNA Synthetases