title: GSM6427523: SUM159 pLV-KRAB + all 4-targeting gRNAs, ATAC-seq; Homo sapiens; ATAC-seq
library_construction_protocol: Cells were grown to ~80% confluency before being dissociated and counted.  Cells were lysed in ATAC resuspension buffer and nuclei were counted before transposition. Tagmentation was performed in 1x Tagmentation Buffer (1M Tris-HCl pH 7.6, 1M MgCl2, 10% Dimethyl Formamide) using 2 µL Tn5 transposase (in-house made Tn5, 25 µg/ml final) in 100 µl final volume, at 37°C for 30 min, 1000 rpm. Tagmentation was inactivated with a final concentration of 0.5% SDS (Merck) and subjected to Proteinase K treatment (NEB) at 55 °C for 15 min at 1000 rpm.  Reaction was purified using a Bioline PCR Clean-up kit and eluted in 25 µL of H2O. PCR was performed using NEBNext High Fidelity PCR master mix with the following conditions: 58 °C for 5 min, 72 °C for 5 min, 98 °C for 30 sec; 11 cycles of 98 °C for 10 sec, 63 °C for 30 sec, 72 °C for 1 min and then 72 °C for 2 min and hold at 12 °C. Final clean-up of product was performed using 1.0x Ampure XP beads and visualized on the Agilent D5000 TapeStation.