XL-DNase-seq: Improved footprinting of dynamic transcription factors

Abstract

Abstract As the cost of high-throughput sequencing technologies decreases, genome-wide chromatin accessibility profiling methods such as the assay of transposase-accessible chromatin using sequencing (ATAC-seq) are employed widely, with data accumulating at an unprecedented rate. However, accurate inference of protein occupancy requires higher resolution footprinting analysis where major hurdles exist, including the sequence bias of nucleases and the short-lived chromatin binding of many transcription factors (TFs) with consequent lack of footprints. Here we introduce an assay termed crosslink (XL)-DNase-seq, designed to capture chromatin interactions of dynamic TFs. Mild crosslinking improved the detection of DNase-based footprints of dynamic TFs but interfered with ATAC-based footprinting of the same TFs. XL-DNase-seq may help extract novel gene regulatory circuits involving previously undetectable TFs. The DNase-seq and ATAC-seq data generated in our systematic comparison of various crosslinking conditions also represent an unprecedented-scale resource derived from activated mouse macrophage-like cells which share many features of inflammatory macrophages.