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. 2024 Oct 24;15:9175. doi: 10.1038/s41467-024-53439-3

Fig. 5. The BceRS three-component system controls an adaptive response.

Fig. 5

A Schematic of the BceRS signalling pathway. The RNA-seq fold change scale in the BceSV124A mutant is shown below the horizontal line. The BceAB transporter is the third component of the regulatory system, predicted to sense and transduce the signal to BceS. Functions currently assigned to each component are indicated by question marks with coloured frames indicating functional category (red: signalling; yellow: sensing and transmission; blue: drug resistance). B BceAB is necessary to activate BceRS signalling in the absence of drugs. Fold changes during exponential growth in rich media were quantified by RT-qPCR in the activated HK+ mutant (BceSV124A: blue), in mutants with a non-phosphorylable variant of the cognate regulator in the WT (BceRD55A: grey) or activated (BceSV124A BceRD55A: red) backgrounds, and in a BceAB transporter mutant in the activated background (BceSV124A ∆bceAB: pink). Bars represent the mean and SD of biological replicates (n = 3). C Growth curves of the WT and activated BceSV124A mutant in the presence of an increasing concentration of drugs. The curves represent the mean and SEM of biological replicates (n = 4). D Drug susceptibilities of double mutants abolishing BceRS activation in the BceSV124A mutant. The curves represent the mean and SEM of biological replicates (n = 3). E Drug susceptibilities of ∆bceP, ∆bceD, and ∆bceO mutants in the activated mutants (left panel) and/or the WT strain (right panel). The curves represent the mean and SEM of biological replicates (n = 3). F Growth curves of the WT strain pre-exposed to nisin. Early exponential growing WT strains were exposed for 4 h to nisin (Adapt 0 to 128 µg/ml) in THY at 37 °C. After washing and OD600 normalisation, each culture is inoculated in fresh, rich media (THY) and with increasing concentrations of nisin (Nisin 64, 128, and 256 µg/ml). The curves represent the mean of two biological replicates (n = 2). Source data for all panels are provided as a Source Data file.