Construct: Ecol\lacZrepo.4.3 in which the 5 gcm protein binding sites (RCCXXCAX) closest to Ecol\lacZ have been mutated (note - all these are 'perfect' consensus sites). Sites mutated (position of relative to repo transcription start given in brackets): (-2562 to -2555) ACCCGCAG -> AAACGTCG; (-2279 to -2286) ACCCACAT -> AAACGTCG; (-2075 to -2068) GCCCGCAT -> AAACGTCT; (-1865 to -1858) GCCCGCAT -> GAACGTGT; (-1465 to -1458) GCCCACAT -> GAACGTGT;