Galactose-specific messenger ribonucleic acid contents in Escherichia coli: effect of inducer, gene dosage and galactose genotype.

Galactose specific mRNA (gal-mRNA) and galactokinase were measured in strains of E.coli with varying numbers of copies of the galactose operon. While the fucose induction the amount of gal mRNA has been found to be proportional to the content of galactokinase and to the gene frequency, with galactose induction this was not the case. It is suggested that this is a result of the metabolism of galactose leading to catabolite repression. The amounts of gal-mRNA and galactokinase were also measured in a series of polar mutants. With increasing polarity, there was a greater effect on enzyme content than on gal-mRNA. This suggests that the effect of polarity on RNA is the result of degradation after synthesis rather than prevention of transcription. A method of correlating hybridisation data with the genetic map is described.