TABLE 3.

In vivo λ N-mediated antitermination assays

The ratios of β-galactosidase activities in the presence (+ter) and absence (−ter) of terminators give the values of terminator read-through (%RT), which is a measure of antitermination efficiency. %RT is defined as the same way as in Table 2. Rho-dependent (P_lac-l t_R1-trpt′-lacZYA; columns 1 and 2) and -independent (P_lac-l nutR-T_R′-T1-T2-lacZYA; columns 3 and 4) terminator cassettes were fused to the lacZ reporter for the assays. The Rho-dependent terminator, t_R1 was derived from the nutR-cro region of phage λ. Measurements were performed both in the absence (−λ N) and presence (+λ Ν) of λ N proteins. ND, not determined.

nusA allels	1 +λ N β- Galactosidase activity			2 −λ N β- Galactosidase activity			3 +λ N β- Galactosidase activity			4 −λ N β- Galactosidase activity
	+tR1-trpt′	−tR1-trpt′	%RT	+tR1-trpt′	−tR1-trpt′	%RT	+TR′-T1-T2	−TR′-T1-T2	%RT	+TR′-T1-T2	−TR′-T1-T2	%RT
	Arbitrary units			Arbitrary units			Arbitrary units			Arbitrary units
WT	475 ± 14	944 ± 6	50.3	ND	ND	ND	425 ± 4	891 ± 86	47.7	6.0 ± 1.0	240 ± 9	2.5
ΔAR2	485 ± 30	937 ± 36	51.8	ND	ND	ND	434 ± 10	754 ± 50	57.5	8.0 ± 1.1	379 ± 19	2.1
ΔAR1–2	442 ± 37	824 ± 34	53.6	ND	ND	ND	347 ± 16	890 ± 78	38.9	10.0 ± 1.2	379 ± 18	2.6