title: GSM4781641: p53 KO 5-FU 300um treated 24h rep2 [ATAC-seq]; Homo sapiens; ATAC-seq
library_construction_protocol: Cells were washed with PBS once, and pelleted down by centrifugation. Nuclei were isolated and accessible DNA tagmented and purified throgh the previous ATAC-seq protocol (Buenrostro et al., 2015). DNA fragments 100 bp - 1 kb were purified with AMPure XP beads and amplified by PCR prior to pooling and sequencing. ATAC-seq libraries were prepared according to Illumina's instructions accompanying the DNA Sample Kit (Part# 0801-0303). Briefly, tagmented accessile DNA was purified by AMPure XP beads, then end-repaired using a combination of T4 DNA polymerase, E. coli DNA Pol I large fragment (Klenow polymerase) and T4 polynucleotide kinase. The blunt, phosphorylated ends were treated with Klenow fragment (32 to 52 exo minus) and dATP to yield a protruding 3- 'A' base for ligation of Illumina's adapters which have a single 'T' base overhang at the 3' end. After adapter ligation DNA was PCR amplified with Illumina primers. Then, the purified DNA was captured on an Illumina flow cell for cluster generation. Libraries were sequenced on the Illumina HiSeq 2500 following the manufacturer's protocols.