Fig. 5: Sequential H1(N76D/N77D) and H1K75ac promote chromatin relaxation and maintain genome stability.

a, Chromatin fractions or WCLs were extracted from H1.4-KO HeLa cells that were transfected with the indicated plasmids, and analysed by an MNase assay (top) or immunoblotting (middle), and the intensity of each lane was quantified (bottom). b, H1.4-KO U2OS-AsiSI-ER-AID cells were transfected with wild-type H1.4 or H1.4-RAA plasmids and treated with or without 4OHT. Cells were subjected to ATAC-seq. Normalized signals of 80 sensitive DSB sites were plotted. c, U2OS-AsiSI-ER-AID cells were treated with or without 4OHT and subjected to ATAC-seq or CUT&Tag-seq with the indicated antibodies. Normalized signals of a representative DSB site is shown. d, H1.4-KO HeLa cells expressing wild-type or mutant Flag–H1.4 were modified to express FKBP–CTPS1, and treated with or without VP16 after being treated with or without dTAGV-1 for 3 h. Chromatin fractions or WCLs were analysed by an MNase assay (top) or immunoblotting (middle). The intensity of each lane was also quantified (bottom). e, The affinity between purified His–H1.4 or His–H1.4-KQ proteins and synthesized DNAs was analysed by an MST assay. f, Wild-type or CTPS1-KO HeLa cells were injected into nude mice, with or without (Ctrl) exposure to IR (n = 6 per group). Growth curves of xenografts are shown. g, Quantification of CTPS1 expression in cervical cancer tissues (n = 58). Blue indicates sensitive patients who survived 5 years after radiotherapy, and red denotes resistant patients who had died within 5 years of radiotherapy. h, Overall survival of patients with survival information in g (n = 48). Blue indicates low CTPS1expression, red denotes high CTPS1 expression. i, Correlation of CTPS1 and H1(N76D/N77D) expression in cervical tumour and para-tumour tissues (n = 57). Data represent the mean ± s.d. (f,g). P values were calculated using Student’s unpaired two-tailed t-tests (f,g), log-rank (Mantel–Cox) test (h) or Pearson r test (i).

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