Table 3.

BoxA Mutations Block NusG Coupling at nutR

Strains	boxA	nusB	β-Galactosidase Activity (λN−) in Miller Units	β-Galactosidase Activity (λN+) in Miller Units	RT (%)
10,673; 10,672	+	+	125 ± 1	946 ± 23	13 ± 0.3
10,675; 10,674	69	+	1,212 ± 30	2,211 ± 87	55 ± 2.5
10,678; 10,677	+	Δ	2,874 ± 24	2,616 ± 103	100 ± 4.4
10,680; 10,679	69	Δ	1,896 ± 25	2,416 ± 80	78 ± 2.8

Expression of lacZ was induced from a chromosomal cII::lacZ transcriptional fusion (λcIts-pR-cro (SD^-) -nutR-tR1-cII::lacZ) by incubation at 42°C for 30 min. Strains N10672, N10674, N10677, and N10679 express λn, which encodes the transcription termination inhibitor λΝ. boxA69 and ΔnusB strain numbers are indicated in Table 3. RT was calculated from the ratio of β-galactosidase activity in the presence or absence of λN (λN ⁺ and λN ^-, respectively). Miller units from ≥3 independent experiments were averaged.