Evolutionary drift of the argF and argl genes. Coding for isoenzyme forms of ornithine transcarbamylase in E. coli K12.

Considerable genetic drift has occurred during the evolution of the two genes, argF and argl, which individually code for isoenzyme forms of ornithine transcarbamylase in E. coli K12. The use of the experimental protocol described in this work established that between 25-40% of the base pairs in the genes argF and argl have changed since they diverged from a hypothetical ancestral gene. The extent of divergence of the genes was determined by mRNA-DNA hybridization utilizing arginine transducing DNA as a hybridization probe and mRNA prepared in vivo from appropriate bacterial strains and with mRNA synthesized in vitro using template DNA isolated from the specialized transducing phages gammacI857dargl and phi80dargF.