1. Molecular mechanism of enhanced xylose utilization by XylR mutations.
Molecular mechanism of enhanced xylose utilization by XylR mutations. (A) Schematic drawing of the xyl operons (gray box) including their transcription start point (arrow). Binding sites of CRP and XylR are indicated as yellow and blue boxes. XylR has two known binding sites, IA and IF. The given size does not reflect real proportions. (B) Relative transcript levels of selected genes of strains CM2 and TL1 with xylR variants R121C and P363S, respectively. The data indicate the fold change of transcript level in relation to the ancestor XW043 background and are normalized by the transcript level of 16S ribosomal RNA (rrsA), n = 4, unpaired Student’s t test indicates significance at *P < (C) Fitted data and (D) the determined dissociation constant (KD) from EMSAs to determine the binding affinity of different XylR variants with their known binding sites, IA and IF, respectively. (E) Modeled structure of the dimeric wild-type XylR (28). The following features are highlighted: xylose (purple), mutated residues (red), and DNA binding domain (blue).
Christian Sievert et al. PNAS 2017;114:28:
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