Single-cell profiling of proteins and chromatin accessibility using PHAGE-ATAC

Multimodal measurements of single-cell profiles are proving increasingly useful for characterizing cell states and regulatory mechanisms. In the present study, we developed PHAGE-ATAC (Assay for Transposase-Accessible Chromatin), a massively parallel droplet-based method that uses phage displaying, engineered, camelid single-domain antibodies ('nanobodies') for simultaneous single-cell measurements of protein levels and chromatin accessibility profiles, and mitochondrial DNA-based clonal tracing. We use PHAGE-ATAC for multimodal analysis in primary human immune cells, sample multiplexing, intracellular protein analysis and the detection of SARS-CoV-2 spike protein in human cell populations. Finally, we construct a synthetic high-complexity phage library for selection of antigen-specific nanobodies that bind cells of particular molecular profiles, opening an avenue for protein detection, cell characterization and screening with single-cell genomics. Protein epitopes and chromatin accessibility are measured in single cells using phage display.

Automated summary

The study introduces a novel method called PHAGE-ATAC for simultaneous single-cell measurements of protein levels and chromatin accessibility profiles, using mitochondrial DNA-based clonal tracing. PHAGE-ATAC is utilized for multimodal analysis in primary human immune cells, sample multiplexing, intracellular protein analysis, and detection of SARS-CoV-2 spike protein. Additionally, a synthetic high-complexity phage library is constructed for selection of antigen-specific nanobodies, enabling protein detection, cell characterization, and screening with single-cell genomics.