Regulation by pyrR regulatory element is important, but not essential for <i>in vitro</i> growth of <i>S</i>. <i>pneumoniae</i>.

(A-B)In vitro growth curves of mutants when cultured in defined media with (20 μg/ml) or without uracil. While mutant M2 (green) does not display a growth defect, mutants M1 (orange) and M3 (maroon) have growth defects that are restored in the presence of uracil indicating that a functional pyrR RNA element is important, but not absolutely essential for in vitro growth of S. pneumoniae. WT (blue) does not have a growth defect in the tested conditions. (C-D) Representative in vitro growth curves of mutants cultured in media with (15 μg/ml) or without 5-FOA, a toxic uracil analog. All strains show varying degrees of defects in the tested conditions indicating that a drug targeted against the secondary structure can severely and specifically hamper growth. Mutant M3 was not included in this assay as it cannot be grown without uracil. Error bars represent standard error of the mean across three biological replicates.