Ultraviolet-Sensitive Mutator Strain of Escherichia coli K-12

L-Serine-sensitive mutants of Escherichia coli K-12.

While attempting to isolate d-serine-sensitive mutants of Escherichia coli K-12, we found a class of mutants sensitive to low concentrations of l-serine (10 to 25 mug/ml).

Temperature-Sensitive Mutants of Escherichia coli K-12

Crosses were carried out at 34 C and 42 C between eight pairs of isogenic strains of Escherichia coli K-12. The donor and recipient of each pair carried the same mutation for temperature-sensitive deoxyribonucleic acid (DNA) synthesis; they differed only in the presence of F-lac in the donor and a spectinomycin-resistance marker in the recipient. A different temperature-sensitive mutation was p...

The beta-d-galactosidase of Escherichia coli, strain K-12.

Further characterization of a non-essential mutator gene in Escherichia coli K-12.

The properties of mutR, a mutator closely linked to thyA, have been further characterized. We have found that the mutator gene is carried on a specialized transducing phage (lambdapcI857 thyA) generated by the excision of lambdacI857 integrated at a secondary attachment site between lysA and thyA. We present three lines of evidence indicating that mutR is a nonessential gene. (i) Deletions of t...

Isolation, characterization, and genetic analysis of mutator genes in Escherichia coli B and K-12.

Twenty-one Mut mutants were obtained from Escherichia coli B (B/UV) and K-12 (JC355) after treatment with mutagens. These Mut strains are characterized by rates of mutation to streptomycin resistance and T-phase resistance which are significantly higher than the parental (Mut(+)) rates. Mutator genes in 12 strains have been mapped at three locations on the E. coli chromosome: one close to the l...