cells were cross-linked in 1.0% formaldehyde. Cells were then lysed by lysis buffer. Chromatin was sonicated by bioruptor to an average size of 150~500 bp. ~ 10 million cells was used for one ChIP-nexus DNA-protein-complexes were isolated with specific antibodies when still being attached to protein A-dynabeads. DNA was end repaired using NEBNext End repair module (#E6050L). A single 3'-A overhang was added to the blunted ends using NEBNext dA-Tailing module (#E6053L). Adapters with single 3'-T overhangs and 5’ overhangs (barcode composed of 5 random nucleotides) were ligated to the adenylated fragments. Ligated fragments were blunted again by Klenow 3'-5' exo- polymerase to fill in the 5’ overhang first and then by T4 DNA polymerase to trim any possible 3’ overhang. Blunted DNA was subsequently digested by lambda exonuclease first and RecJf afterwards. Digested single strand DNA was then eluted, reverse cross-linked and purified prior to self-circularization by Circligase. An oligonucleotide was mixed with circularized single DNA for subsequent BamHI digestion to linearize the single DNA again. Linearized single strand DNA was then PCR-amplified using adaptor sequences and library was purified on 2% agarose gel to remove adaptor-adaptor ligation products. Following cluster generation on the flowcell surface, the sequencing libraries were sequenced following Illumina's protocol.
GEO Accession
GSM2523062