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. 2016 Oct 10;8(6):993–1004. doi: 10.1080/21505594.2016.1244589

Figure 2.

Figure 2.

Lm ESX-1 system is weakly expressed but functional. (A) Expression of ESX-1 genes in standard growth conditions. The expression of esxA, esxB, essC and essB was analyzed by RT-PCR on total RNAs extracted from logarithmic cultures grown in BHI at 37°C. inlA, actA and iap were used as control genes. (B) Expression of esxA at exponential (Exp) and stationary (Stat) phase of growth measured by RT-PCR (left panel) and qRT-PCR (right panel). Expression value in stationary phase is expressed relative to the value obtained in exponential growth phase. (C) SigB-independent expression of esxA. qRT-PCRs performed on total RNAs extracted from WT and ΔsigB strains at the exponential (left panel) and stationary (right panel) phase of growth in BHI at 37°C. bsh was used as control gene whose expression is SigB-dependent. Gene expression levels in the ΔsigB mutant were normalized to those in the WT. (B and C) Values are mean ± SD (n = 3). (D) Secretion of EsxA is dependent on EssC. Detection of myc-tagged EsxA protein (EsxA-myc) in supernatants of Lm EGDe+esxA-myc (WT+esxA-myc) at different stages of growth (OD600nm = 0.7, 1.4 and 1.8) (Left panel), and in total bacterial lysates and supernatants from WT, WT+esxA-myc, ΔessC, ΔessC+esxA-myc and ΔessC+essC+esxA-myc strains in exponential growth phase (Right panel).