title: Temperature-dependent retention of a tryptophan-operon-bearing plasmid in Escherichia coli.
abstract: Derivatives of plasmid pBR322 carrying the tryptophan operon are rapidly lost from a growing culture. The valS gene from Escherichia coli was combined with the tryptophan operon on a pBR322 derivative, pSGS21. In a thermosensitive valS mutant of E. coli K-12 host, plasmid pSGS21 was stably inherited for over 200 generations at temperatures nonpermissive for the chromosomal mutation. At 30 degrees C, a temperature at which the host valSts protein is functional, the plasmid was lost at a rate of 1.2% per cell generation.
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005798:Genes, Bacterial; D005822:Genetic Vectors; D009876:Operon; D010957:Plasmids; D013696:Temperature; D014367:Tryptophan Synthase / Q000235:genetics; D014637:Valine-tRNA Ligase / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D014367:Tryptophan Synthase; D014637:Valine-tRNA Ligase