Fig. 1.

Histone PTMs in P. tricornutum. a Sites of PTMs of linker, core and variant histones identified in this work. Amino acid residue number is indicated below the peptide sequence. Gray, black and white boxes indicate N-terminal, globular core and C-terminal domains, respectively. Because K211 and K212 are contiguous, their methylation state cannot be discriminated. Me2 can be located on K211 or K212 of histone H1. H3K9me2 and H3K9me3 were detected by western blot. Novel modifications are underlined. b Novel histone modifications are modeled on the crystal structure of the nucleosome (Protein Data Bank file 3A6N). The histone proteins are shown in ribbon diagram with histone H2A in red, H2B in orange, H3 in blue, and H4 in green. The DNA helix is shown in gray. Modified residues are visible as yellow spheres. The image was generated using the program Pymol [24]