Fig. 5: Predicted CDC45-USP37 interaction surface is important for USP37 function at the replisome.

a Xenopus sperm chromatin was incubated in egg extracts with indicated inhibitors for 10 min, recovered and blotted. See also Supplementary Fig. 10b. b Right, the predicted structure in Supplementary Fig. 10f aligned to the structure of human CMG (PDB:7pfo). Left, the same model rotated 90°. Orange dashed line, disordered region. c Xenopus sperm chromatin was incubated in egg extracts supplemented with WGE-expressed recombinant USP37 variants, recovered and blotted. Geminin was added where indicated to block replication. See also Supplementary Fig. 11a, b. d Plasmid DNA was incubated in the indicated egg extracts with different WGE-expressed recombinant USP37 variants, ICRF-193 and p97-i as indicated, recovered and blotted. Samples are from the same experiment, blots processed in parallel. See also Supplementary Fig. 11c, d. Abbreviations as in Supplementary Fig. 10k. e Extracts of HEK293T cells expressing mCherry (empty vector, EV), mCherry-USP37^WT, or mCherry-USP37^8A were subjected to mCherry immunoprecipitation (IP) followed by immunoblotting. n = 3 independent experiments. f Representative images of USP37-EdU PLA. Scale bar: 10 μm (left); Dot plot indicating the number of PLA foci between mCherry-tagged EV, USP37^WT, USP37^C350, or USP37^8A and EdU (replicating DNA) in untreated- or camptothecin-treated cells (right). Untreated: n = 291 (EV), 329 (WT), 307 (C350), 287 (8A) cells; camptothecin: n = 197 (EV), 320 (WT), 287 (C350), 300 (8A) cells. Bar, median of three independent experiments. Black dots, means in each biological replicates. Statistics reflect two-tailed Wilcoxon rank-sum tests for p values without adjustment for multiple hypothesis testing and Cohen’s d for effect sizes (γ). g, h Clonogenic survival assays of control (CTRL) or USP37 KO (clone 10) cells expressing mCherry (EV), mCherry-USP37^WT, or mCherry-USP37^8A treated with camptothecin (g) or etoposide (h). CTRL + EV and USP37 KO+ mCherry-USP37^WT samples are as in Fig. 1h, i. n = 3 independent experiments. Bars represent means ± SEM. Statistical analysis for (g, h) with two-way ANOVA and Šídák test for multiple comparisons. i Clonogenic survival assays of USP37 KO cells expressing mCherry (EV), mCherry-USP37^WT, or mCherry-USP37^8A transduced with a control or TRAIP-targeting sgRNA upon treatment with camptothecin. Bars, means ± SEM. Statistical analysis with two-way ANOVA and Holm-Šídák test for multiple comparisons. Source data provided as a Source Data file.