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Fig. 3 | BMC Genomics

Fig. 3

From: Conserved and specific features of Streptococcus pyogenes and Streptococcus agalactiae transcriptional landscapes

Fig. 3

Variations in strain S119 transcriptome in response to high Mg2+ concentrations. Left: IGV captures of RNA-seq coverages in conditions of late exponential growth phase in THY broth supplemented (Mg2+) or not (THY) with 15 mM MgCl2 and TAP+/TAP results of dRNA-seq experiments, shown on the (+) and (−) strands and schematic views of TU organizations. Right: Log2 values of the expression fold-changes (FC) between samples prepared at high versus low Mg2+ concentrations. Mean value±SEM (N = 3). a. Down-regulation of csRNA15-rivR TU in conditions of high Mg2+ concentration; b Inverse regulation of pts-lacABCD.1 operon and of the lacABCD antisense transcript, in response to variations in Mg2+ concentration. c Up-regulation of the speB-spi operon at high Mg2+ concentrations; the two TSS at − 696 and − 841 relative to the translation initiation codon for speB are indicated by thin arrows while a major cleavage site located at − 137 and associated with a TAP+/TAP- ratio close to 1 is shown by a blue triangle. The speB-spi transcript 5′ UTR overlapped the 5′ UTR of the ropB transcript, whose TSS was characterized 368 nt upstream of ropB translation initiation codon. The CDS encoding the recently described peptide SIP [64] from the speB-spi 5’UTR is indicated. A potential initiation codon is also present three nucleotides after the ropB TSS, a configuration reminiscent of leaderless RNAs that would give rise to a 26 amino-acid peptide we annotated as SP119_1712. Differential expression analysis of the 5’UTR associated with the two speB-spi TSS showed that both promoters were affected by Mg++ status. While no increase in ropB expression was detected over the CDS, a two-fold increase in the coverage of SP119_1712 was observed in Mg-rich medium, suggesting a supplementary level of regulation on ropB

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