FIG 4.

Effect of csRNA1-1 mutation on PilT expression. (A, left) Putative secondary structure of csRNA1-1, as predicted by Mfold (41). The nucleotides involved in the putative region for hybridization with pilT mRNA are highlighted in gray background. (Right) Putative interactions between the 5′ end of pilT mRNA and csRNA1-1 WT or mutant strains (mut-1, mut-2, and mut-3). The ribosome binding site and start codon are underlined. Substituted nucleotides in csRNA1-1 mutants are shown in plain lowercase. (B) Luciferase activity of S. sanguinis csRNA1-1 mutant strains (mut-1, mut-2, and mut-3). Strains were grown in BHI broth to early exponential phase and luciferase activity was measured. Data are presented as percent luciferase activity relative to that of the WT-luc strain. Data are expressed as means ± SD from triplicate experiments. *, P < 0.01. (C) RT-PCR analysis of csRNA1-1 expression in S. sanguinis csRNA1-1 mutant strains. Strains were grown to early exponential phase, and RNA was isolated and used in RT-PCR analysis. The image shown is representative of three independent experiments.