Regulation of newly evolved enzymes. II. The ebg repressor

The ebg (evolved beta-galactosidase) regulatory locus has been mapped. The map order is argG-ebgA-ebgR-tolC-metC, and there is 1.6% recombination between ebgR and ebgA. Studies with ebgR-/ebgR+ merdiploids have shown that ebgR- is recessive, and it is concluded that the synthesis of ebg enzyme is under negative control.