Genome-wide single-cell and single-molecule footprinting of transcription factors with deaminase.

Decades of research have established that mammalian transcription factors (TFs) bind to each gene's regulatory regions and cooperatively control tissue specificity, timing, and intensity of gene transcription. Mapping the combination of TF binding sites genome wide is critically important for understanding functional genomics. Here, we report a technique to measure TFs' binding sites on the human genome with a near single-base resolution by footprinting with deaminase (FOODIE) on a single-molecule and single-cell basis. Single-molecule sequencing reads after enzymatic deamination allow detection of the TF binding fraction on a particular footprint and the binding cooperativity of any two adjacent TFs, which can be either positive or negative. As a newcomer of single-cell genomics, single-cell FOODIE enables the detection of cell-type-specific TF footprints in a pure cell population in a heterogeneous tissue, such as the brain. We found that genes carrying out a certain biological function together in a housing-keeping correlated gene module (CGM) or a tissues-specific CGM are coordinated by shared TFs in the gene's promoters and enhancers, respectively. Scalable and cost-effective, FOODIE allows us to create an open FOODIE database for cell lines, with applicability to human tissues and clinical samples.