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Integrative Genomic Analysis Identifies Isoleucine and CodY as Regulators of Listeria monocytogenes Virulence

Figure 5

CodY regulates the transcription of virulence and metabolic genes under limiting concentrations of BCAAs.

A. Relative luminescence measurements (RLU) indicating activation of hly promoter under growth of WT L. monocytogenes (harboring pPL2-Phlylux plasmid) in BHI, MDM and MDM with low concentration of isoleucine. B. Optical density measurements of the same cultures of WT L. monocytogenes containing pPL2-Phlylux plasmid, growing in BHI, MDM and MDM with low concentration of isoleucine. The results represent 3 independent experiments (N = 3). Error bars indicate a standard error of the mean. C. Relative luminescence measurements indicating activation of hly promoter in ΔcodY mutant and WT bacteria during growth in MDM and MDM with low concentration of isoleucine. The results represent 3 independent experiments (N = 3). Error bars indicate a standard error of the mean. D. RT-qPCR analysis of prfA and actA transcription levels during growth in MDM with low levels of isoleucine in the ΔcodY mutant, WT bacteria and ΔcodY complemented strain harboring pPL2-codY plasmid with and without IPTG. Levels are represented as RQ, relative to BHI and normalized to rpoD mRNA. The data represent 3 independent experiments (N = 3). Error bars indicate a 95% confidence interval. E. RT-qPCR analysis of ilvC and purH transcription levels in ΔcodY mutant and WT bacteria during growth in BHI and in MDM media with reduced concentrations of BCAAs: 100 µg/ml and 10 µg/ml. Represented as RQ, relative to BHI and normalized to rpoD mRNA. The data represent 3 independent experiments (N = 3). Error bars indicate a 95% confidence interval. In all experiments (A–E) overnight precultures were grown in MDM. F. Intracellular growth curve of the ΔcodY mutant, WT bacteria and the ΔcodY complemented strain (with and without IPTG) in primary BMD macrophage cells. The data represent 3 independent experiments (N = 3). Error bars indicate a standard error of the mean.

Figure 5

doi: https://doi.org/10.1371/journal.pgen.1002887.g005