. 2013 Aug;195(15):3412–3423. doi: 10.1128/JB.02213-12

Table 2.

Effect of phosphate on pssA-lacZ transcription in R. leguminosarum bv. trifolii 24.2 and S. meliloti strains

Plasmid	Pho box genotype^d	β-Galactosidase activity by strain and condition^a
		24.2 (wild type)			Rm1021 (wild type)			RmH406 (phoB mutant)
		Low P_i^b	High P_i^b	P_i ratio^c	Low P_i	High P_i	P_i ratio	Low P_i	High P_i	P_i ratio
pPA1	1, 2, 3	8,127 ± 489	4,780 ± 386	1.70*	20,720 ± 954	16,538 ± 890	1.25	8,904 ± 664	9,659 ± 682	0.92
pPA2	1, 2, 3	6,784 ± 392	4,111 ± 312	1.64*	19,182 ± 886	15,978 ± 925	1.20	9,694 ± 564	10,467 ± 773	0.93
pPA3	1^†, 2, 3	3,867 ± 302	2,595 ± 217	1.49*	15,045 ± 790	12,470 ± 788	1.21	8,279 ± 669	8,301 ± 532	0.99
pPA4	2, 3	3,120 ± 261	1,950 ± 186	1.60*	24,597 ± 1,288	20,169 ± 1,176	1.22	12,402 ± 821	12,996 ± 863	0.95
pPA4-A	2^†, 3	1,574 ± 122	1,345 ± 102	1.17	9,265 ± 757	8,659 ± 678	1.07	6,882 ± 489	6,681 ± 512	1.03
pPA4-B	3	484 ± 59	457 ± 54	1.06	2,082 ± 189	2,169 ± 231	0.96	1,415 ± 162	1,459 ± 128	0.97
pPA4-C	2	2,813 ± 211	1,888 ± 157	1.49*	19,288 ± 1,136	16,209 ± 1,106	1.19	10,885 ± 926	10,672 ± 995	1.02

The cultures were inoculated to an OD₆₀₀ of 0.1 and grown for 24 h at 28°C in M1 minimal medium supplemented with different concentrations of phosphate, Tc (10 μg ml⁻¹), and 1% glycerol. Low-phosphate medium additionally contained 20 mM MOPS for pH stabilization. pssA-lacZ transcription was determined from β-galactosidase assays.

Values (Miller unites) are means ± standard deviations of three independent experiments. Low P_i, 0.1 mM phosphate; high P_i, 15 mM phosphate.

P_i ratio, activity at low P_i/activity at high P_i. *, statistically significant difference (P < 0.05) between low- and high-phosphate conditions for the individual fusion assayed.

Numbers refer to Pho boxes (Fig. 1). †, 3′ half.