. 2002 May;184(9):2447–2454. doi: 10.1128/JB.184.9.2447-2454.2002

TABLE 3.

Levels of Par proteins affect transcription block

Plasmid	par operon	Level of par operon expression^a	Miller units^b
pALA1855	p_cparA⁺parB⁺	0.5×	340
pALA2310	p_cparA⁺parB⁺	10×	197
pALA2306	p_cparA⁺parB⁺	20×	183
pALA1856	p_cparAM314I parB⁺	0.5×^c	353
pALA2312	p_cparAM314I parB⁺	10×^c	15
pALA2308	p_cparAM314I parB⁺	20×^c	14

Each par operon has a constitutive promoter. Plasmids are described in Materials and Methods. Plasmids pALA2306 and pALA2308 have the Par operon inserted in the vector pGB2 in orientation 1, such that the operon is transcribed in the same direction as Sp resistance (see Materials and Methods). Plasmids pALA1855 and pALA1856 also have the operon inserted into pGB2 but in the opposite orientation. Levels of operon expression were estimated by measuring the ParA content of the cells (see Materials and Methods). The 1 × level of expression is defined as the level of ParA expression in lysogens of λ-P1:5RKm.

The β-galactosidase assays were carried out after induction of the lacZ gene with 1 mM IPTG in strain CC4248 carrying the relevant plasmid (see Materials and Methods). Values are averages of at least three experiments.

The level of ParA protein was not determined for these cells but was inferred to be the same as the relevant wild-type parA⁺ constructs, as they have the same promoter.