Fig. 2.

RARE prevents Rho-dependent termination in the mgtCBR leader RNA. (A) Schematic of two alternative conformations that the 5′ end of the mgtCBR leader RNA can adopt (18). Positions of insertions are indicated by arrows, deletions and substitutions by brackets, and mutations that selectively destabilize stem-loops A and B by numbers in bold face. The calculated ∆G values for stem-loops A and B are −14.8 kcal/mole and −17.8 kcal/mole, respectively. (B) Fluorescence levels exhibited by wild-type Salmonella (14028s) harboring a plasmid that contains a transcriptional fusion between the wild-type mgtCBR promoter and leader, or mgtCBR leader variants, to a promotorless gfp gene. (−) corresponds to wild-type Salmonella (14028s) harboring the plasmid vector pFPV25. Shown are the mean and SD from at least three independent experiments. (C) gfp mRNA levels produced by wild-type Salmonella (14028s) harboring a plasmid with a transcriptional fusion of the wild-type mgtCBR promoter and leader, or mgtCBR leader variants with the Cs at positions 109–112 substituted by AUGU, or deleted for nucleotides 79–103 (∆stemB), to a promotorless gfp gene. mRNA levels were determined by qRT-PCR. Cells were harvested after 3 h growth in N-minimal medium with 10 μM Mg²⁺ followed by a 15-min treatment with BCM. (−) corresponds to wild-type Salmonella (14028s) harboring the plasmid vector pFPV25. Shown are the mean and SD from at least three independent experiments.