Fig. 5: Dynamic monomer-dimer equilibrium of PprI.

a The left panel shows DG-PprI dimer in a face-to-face fashion in PprI-ssDNA structure. Two DG-PprI protomers are labeled and colored in distinct colors (protomer A in slate and cyan; protomer B in wheat and yellow). The His72 residue of β-pin is labeled and shown as stick. The right panel shows the close view of His72 interactions at the face-to-face dimer interface. b Superposition of two PprI dimer configurations with distinct colors (face-to-face dimer in slate and wheat; side-by-side dimer in black). c Size exclusion chromatography of wild-type (WT) DG-PprI and dimer-interface mutants (2mut: double-mutant at side-by-side interface, 4mut: quadruple-mutant at face-to-face interface, and 6mut: combined double- and quadruple-mutant) on Superdex 200 10/300 GL column. The peaks correspond to monomeric or dimeric PprI proteins are labeled. d Cleavage (lanes 2−5) and ssDNA activation (lanes 6-13) assays of the dimer interface mutants (2mut, 4mut, and 6mut). The reaction conditions is the same as in Fig. 3d. e Phenotypic analyses of the DG-PprI comlementary strains (dimer interface mutants) following 4 kGy gamma radiation treatments. f Quantitative real-time PCR analysis of the gene expression levels of recA, uvrD, and ddrO were performed as in Fig. 3f. Data represent the means of the three replicates, and the bars represent their standard deviations. One-way ANOVA method followed by Tukey’s post-hoc test was performed to compare the significant differences: ***p < 0.001 and ****p < 0.0001. Source data are provided as a Source Data file.