Abstract
By using rifampicin to increase the rate of β and β′ synthesis in a heterodiploid strain of E. coli carrying the mutation rif pr (Km7), which codes for a rifampicin sensitive RNA polymerase to which the drug binds weakly, and the dominant mutation rif D R , which codes for a rifampicin resistant RNA polymerase, the concentration of these subunits in the cell was increased 1.6 fold. Measurements made after removal of rifampicin from the cells showed that the excess β and β′ subunits did not reduce the rate of their own synthesis below normal.