APPARENT MUTAGENIC EFFECT OF THYMINE DEFICIENCY FOR A THYMINE-REQUIRING STRAIN OF ESCHERICHIA COLI

Improved Method for the Isolation of Thymine-requiring Mutants of Escherichia Coli.

Thymine-requiring mutants of Escherichia coli were rarely found before the observation by Okada, Yanagisawa, and Ryan (Z. Vererbungslehre 92:403, 1961) that cultures of bacteria grown in the presence of high concentrations of aminopterin, thymine, purines, and serine contain a surprising number of cells unable to synthesize their own supply of thymine. They showed that these thymine-dependent m...

The thymine-thymine pyrimidine-pyrimidone(6-4) ultraviolet light photoproduct is highly mutagenic and specifically induces 3' thymine-to-cytosine transitions in Escherichia coli.

We have constructed single-stranded, M13-based vectors that contain a specifically located thymine-thymine pyrimidine-pyrimidone(6-4) UV photoproduct and have used these to estimate the frequency and accuracy of DNA replication past this adduct in uvrA6 cells of Escherichia coli. Both the normal and the Dewar valence photoisomer of the (6-4) adduct were studied. In the absence of SOS induction,...

Technique for starvation of Escherichia coli of thymine.

Loss of deoxyribonucleic acid-thymine during thymine starvation of Escherichia coli.

A substantial loss of deoxyribonucleic acid-thymine occurs during thymine starvation of several thymine auxotrophs derived from Escherichia coli strains B, 15, and K-12.

Inability of low thymine-requiring mutants of Escherichia coli lacking phosphodeoxyribomutase to be induced for deoxythymidine phosphorylase and deoxyriboaldolase.

In a previous communication (T.R. Breitman and R. M. Bradford, Biochim. Biophys. Acta 138:217, 1967), we reported that Escherichia coli 70V3, a low thymine-requiring mutant of Escherichia coli 15, lacked deoxyriboaldolase activity, establishing a biochemical basis for the low requirement. Also presented were data indicating that both deoxythymidine phosphorylase and deoxyriboaldolase were induc...