title: Isolation of recombinant plasmids and phage carrying the lexA gene of Escherichia coli K-12.
abstract: The lexA gene of Escherichia coli K-12 was cloned from the plasmid pLC44-14 into pBR322. Plasmids carrying lexA+ were selected by their ability to complement a recessive tsl mutation, which is believed to be a mutation in lexA. The smallest lexA+ recombinant plasmid, pJL21, contained an EcoRI-PstI fragment 2.9 kilobases (kb) in length; two larger plasmids also contained this fragment, and genetic material to one or both sides of the EcoRI-PstI fragment. Plasmids homologous to pJL21, but carrying a dominant mutation, lexA3, or one of three recessive amber mutations in lexA, termed spr, were also isolated. To clone the EcoRI-PstI fragment onto a lambda vector, the PstI end was first converted to an EcoRI end by attachment of a 100-base pair PstI-EcoRI fragment isolated from the plasmid ColE1; the resultant EcoRI fragment was then cloned into the lambda vector lambda gt4. A restriction map of pLC44-14 was obtained for nine restriction enzymes. The orientation of this map was determined relative to the E. coli genetic map by complementation of the gene ubiA+ and by comparison with restriction enzyme digests of another plasmid, pLC11-9, which carries dnaB, a gene closely linked to lexA, but does not carry lexA.
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D010582:Bacteriophage lambda / Q000235:genetics; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D003001:Cloning, Molecular; D004260:DNA Repair; D004262:DNA Restriction Enzymes; D004926:Escherichia coli / Q000235:genetics*; D005822:Genetic Vectors; D010957:Plasmids; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein
chemical_list: D001426:Bacterial Proteins; D004262:DNA Restriction Enzymes; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein