Fig. 6: The iDDR of TRF2 inhibits MRN endonuclease activity in vitro.
From: DNA-PK and the TRF2 iDDR inhibit MRN-initiated resection at leading-end telomeres
a, Coomassie-stained SDS–PAGE gel of purified TRF2 proteins. The gel is a representative of three independent protein preparations. WT and ∆iDDR were prepared identically. Protein molecular weight (MW) is shown as control. b, Schematic of the MRN–CtIP endonuclease assay with DNA-PK. c, MRN endonuclease assay in the presence of WT or ΔiDDR TRF2. MRN (50 nM) was incubated with phosphorylated CtIP (80 nM), DNA-PKcs (10 nM), Ku70/80 (10 nM) and varying concentrations of TRF2 (25, 50, 100 or 200 nM) in the presence of a 5′ 32P-labeled DNA substrate. The gel is a representative example of two independent replicates. The blue arrow indicates the primary endonucleolytic cleavage product (~45 nt away from the end). d, Schematic of the MRN exonuclease assay. e,f, MRN endonuclease assay gel (e) and quantification (f) of n = 4 independent replicates in the presence of WT or ΔiDDR TRF2. Data are presented as mean ± s.d. Statistics by two-tailed unpaired t-test assuming a Gaussian distribution. ****P < 0.0001, ***P < 0.001, **P < 0.01, *P < 0.05.
