Jung, C. et al. Cell 170, 35–47 (2017).

Recycling has many benefits, as Jung et al. demonstrate on a repurposed MiSeq next-generation sequencing chip with 20 million spatially registered, unique DNA sequence clusters. On their chip-hybridized association-mapping platform (CHAMP), the DNA is labeled with a fluorescent maker and overlaid with fluorescent proteins. The researchers then record fluorescent intensity at each DNA cluster using a total internal reflection microscope. Computational analysis tells them which proteins bind to which DNA sequences. They apply CHAMP to a type-I CRISPR–Cas effector complex and show that this Cascade complex binds a six-nucleotide PAM. CHAMP also allows them to characterize off-target binding and develop a biophysical model for Cascade–DNA interactions.