Ultraviolet-Sensitive Mutator Strain of Escherichia coli K-12

Eli C. Siegel
1973 Journal of Bacteriology  
An ultraviolet (UV)-sensitive mutator gene, mutU, was identified in Escherichia coli K-12. The mutation mutU4 is very close to uvrD, between metE and ilv, on the E. coli chromosome. It was recessive as a mutator and as a UV-sensitive mutation. The frequency of reversion of trpA46 on an F episome was increased by mutU4 on the chromosome. The mutator gene did not increase mutation frequencies in virulent phages or in lytically grown phage A. The mutU4 mutation predominantly induced transitional
more » ... uced transitional base changes. Mutator strains were normal for recombination and host-cell reactivation of UVirradiated phage Ti. They were normally resistant to methyl methanesulfonate and were slightly more sensitive to gamma irradiation than Mut+ strains. UV irradiation induced mutations in a mutU4 strain, and phage A was UV-inducible. Double mutants containing mutU4 and recA, B, or C were extremely sensitive to UV irradiation; a mutU4 uvrA6 double mutant was only slightly more sensitive than a uvrA6 strain. The mutU4 uvrA6 and mutU4 recA, B, or C double mutants had mutation rates similar to that of a mutU4 strain. Two UV-sensitive mutators, mut-9 and mut-10, isolated by Liberfarb and Bryson in E. coli B/UV, were found to be co-transducible with ilv in the same general region as mutU4. amino acids, thymine, and adenine were used at a final concentration of 50 ug/ml. Nutrient broth contained 0.8% (w/v) nutrient broth powder (Difco), 0.1% yeast extract (Difco), and 0.5% sodium chloride. Nutrient and minimal agar were made by adding 20 g of agar (Difco) per liter to the liquid media. L broth and agar (30) were adjusted to pH 7.0. L medium contained 2.5 x 10-3 M CaCl, when Ca2+ was 145 on May 9, 2020 by guest
doi:10.1128/jb.113.1.145-160.1973 fatcat:jwphataaufcazlkhy32hjb6oci