DNA curtains to visualize chromatin interactions.

• A simple method for fluorescently labeling yeast histones and how to re-fold them into H2A-H2B dimers and H3/H4 tetramers. • A labeling strategy for histone sub-complexes. • A method for real-time visualization of nucleosomes on dsDNA. Recent advances in single molecule imaging have allowed the evolution of biochemical techniques that directly visualize protein-DNA interactions in real-time. These techniques rely on diffraction limited total internal reflection microscopy (TIRFM), and have significantly improved our understanding of RNA transcription, DNA replication, homologous recombination, and general DNA repair in the context of chromatin. Here we described a general single molecule TIRFM technique called DNA curtains to directly visualize how enzymes function on chromatinized DNA. The goal of this manuscript is to introduce the reader to methods to express and reconstitute nucleosomes on long stretches of DNA, and to directly visualize this process using DNA curtains with TIRFM. [ABSTRACT FROM AUTHOR]