Fig. 2: BRCA1–BARD1 promotes WRN-mediated DNA unwinding.
From: Mechanism of BRCA1–BARD1 function in DNA end resection and DNA protection
a, A schematic of the single-molecule magnetic tweezers assay setup used and the DNA substrate. b, Representative trajectory of DNA unwinding events by WRN in the presence of RPA, both 25 nM. A zoomed-in view highlighting unwinding and rewinding events is shown in the dashed square. Scale bar, 10 s. c, Representative trajectory of DNA unwinding events by WRN (25 nM) in the presence of BRCA1–BARD1 (40 nM) and RPA (25 nM). d,e, Processivity histogram (d) and cumulative (Cum.) probability distribution (shown as survival probability) (e) of the observed DNA unwinding events by WRN-RPA, both 25 nM, in the absence (grey) or presence (pink) of BRCA1–BARD1 (40 nM), with mean values of 160 ± 14 bp (n = 104) and 283 ± 26 bp (n = 98), respectively. Error, 2 s.e.m. f,g, Velocity histogram (f) and cumulative probability distribution (shown as survival probability) (g) of the observed DNA unwinding events by WRN-RPA, both 25 nM, in the absence (grey) or presence (pink) of BRCA1–BARD1 (40 nM), with mean values of 26 ± 3 bp per second (n = 104) and 34 ± 4 bp per second (n = 98), respectively. Error, 2 s.e.m. h, Ratio of rewinding (DNA shortening) and unwinding (DNA extension) events by WRN-RPA, both 25 nM, in the absence (grey) or presence (pink) of BRCA1–BARD1 (40 nM). Averages shown; error bars, s.e.m.; n = 15 (in the absence of BRCA1–BARD1) and n = 7 (in the presence of BRCA1–BARD1). i, Representative protein-interaction assays. Top, a schematic of the assay. Source data are provided in Supplementary Fig. 1. nt, nucleotides; s, second.
