NMR titration experiment

The NMR titration experiments on ¹⁵N‐labeled HigA^19–97 with the promoter dsDNA Pal‐III (Table S3) were conducted by acquiring the ¹H‐¹⁵N HSQC spectra. Throughout the NMR titration experiments, the concentration of the HigA^19–97 dimer was maintained at 0.5 mm, and the concentration of the promoter dsDNA was increased from 0 to 0.1 mm. The chemical shift perturbation (CSP) was calculated and analyzed using Equation 1, where Δδ_N and Δδ_H are the CSP values of the amide nitrogen and proton, respectively. The intensity ratio was calculated by dividing the peak intensity of the last spectrum by the peak intensity of the first spectrum: