Figure 8

Model of the location and timing of H2A PTMs pre and post deposition during embryogenesis. (A) N-terminal amino acid sequence of Xenopus laevis canonical H2A and H2A.X-F. The modifications we observed by antibody or by mass spectrometry are illustrated: α-N-acetylated and lysine acetylation (green), Ser 1 phosphorylation (blue), Arg 3 mono-methylation (red) and dimethylation (purple). (B) Summary of R3 methylation (me1 and me2) and phosphorylation (ph) found on pre-deposition H2A (red) and H2A.X-F (blue) in the oocyte and laid egg soluble fractions, where they are bound to the chaperone Nucleoplasmin. * = PTMs not observed in immunoblots, ° = only observed in immunoblots. Oocyte histone PTMs were not assayed by mass spectrometry so the cartoon in the left-most column only represents immunoblot data. Co-occupancy of PTMs on a single histone tail was solely identified by mass spectrometry. (C) Summary of R3 methylation and phosphorylation found on chromatin associated H2A and H2A.X-F in embryos. PTMs found on pre-mid blastula transition (MBT) embryos are shown on the left, while post-MBT embryos are shown on the right. * = PTMs not observed in immunoblots, ° = PTMs only observed in immunoblots. The boxed legend references panels B and C. Co-occupancy of PTMs on a single histone tail was solely identified by mass spectrometry.