Figure 1

Representation of the H3K27-trimethylation biosensor (H3K27-MetBio). The biosensor is a four-part genetic chimera composed of the FRET donor mTFP1 [18], a domain that binds to methylated lysine residues, residues 20 to 33 of histone H3 (GenBank: CAA40407), and the FRET acceptor mCitrine [37]. The first (L1), second (L2), and third (L3) linkers are represented with dotted lines. L1 starts immediately after residue 225 of mTFP1 and ends immediately before residue 1 of the chromodomain. L2 starts immediately after the last residue of the chromodomain and ends immediately before residue 21 of the histone H3-derived substrate. L3 starts immediately after the last residue of the substrate and ends immediately before residue 6 of mCitrine. This biosensor design has been previously reported [9].