Figure 1.

Peptide reagents to probe chromocenters. (A) Scheme of a chromocenter containing heterochromatin established via nucleosome cross-bridging by HP1 proteins that bind H3K9me3. Moreover, HP1 proteins may phase-separate to form HP1 droplets surrounding the heterochromatin focus. Peptides containing an HP1 binding site can invade the subcompartment and deliver a payload (i.e., a dye) for imaging of the chromatin state. (B) General design of the peptide reagents containing a scaffold (S) to which chromatin targeting peptides (T), cell-penetrating- or nucleus-targeting moieties (N/C), and a fluorescent payload (F) can be attached. A table of the explored combinations is provided below. For all synthesized peptides and probes, see Tables S1 and S2.