The lysate was sheared into 200- to 1000-bp fragments and Sp9-DNA complex was isolated with specific Sp9 antibody. The yield of ChIP DNA was determined via Quant IT fluorescence assay (Life Technologies) and enrichment efficiencies of ChIP reaction were evaluated by qPCR. Illumina sequencing libraries were generated with NEBNext® Ultra™ DNA Library Prep Kit (New England Biolabs) by following the manufacturer's manual. The library quality was determined by using Agilent 2100 Bioanalyzer(Agilent), and then, subjected to high-throughput 150 base paired-end sequencing on Illumina Hiseq sequencer according to the manufacturer’s recommended protocol.