Figure 4. Effect of the RovA protein on the promoter activities of the regulated loci.

Y. pestis strain 201 and the ΔrovA mutant harboring empty vector pRW50 or pRW50 derivatives containing the corresponding promoters were grown in TMH without calcium at 26°C to an OD₆₀₀ of 1.0, and then transferred to 37°C for of 3 more hours of incubation. β-Galactosidase activities in Miller units were shown for promoter activities of yscN, yscA, lcrG and yopN (A), and for promoter activities of psaA, yopQ, yopJ, yopT and ompC (B). Data shown are the mean values of three independent experiments with the standard deviations indicated. The difference of β-galactosidase activities between the wild type strain and the ΔrovA mutant were calculated using Student's t test, and a p value of <0.05 was taken as statistically significant. The p value is indicated as follows: p<0.05 *, p<0.01 **, p<0.001 ***.