Mutagenic specificity of N4-hydroxycytidine.

The mutagenic specificty of (oh)4Cyd was examined with T4rII phage mutants which allow for discrimination between AT yields GC and GC yields AT base transitions. AT yields GC transitions were induced with a frequency 1-2 orders of magnitude higher than GC yields AT transitions. The mechanism of this preferential transition pathway is discussed in the light of base-analogue mutagenesis.