Aurora1 phosphorylation activity on histone H3 and its cross - talk with other post - translational histone modifications in Arabidopsis . The enzymological properties of AtAurora1 , a kinase responsible for the cell cycle - dependent phosphorylation of histone H3 at S10 , and its cross - talk with other post - translational histone modifications , were determined . In vitro phosphorylation of H3S10 by AtAurora1 is strongly increased by K9 acetylation , and decreased by K14 acetylation and T11 phosphorylation . However , S10 phosphorylation activity is unaltered by mono - , di - or trimethylation of K9 . An interference of H3K9 dimethylation by SUVR4 occurs by a pre - existing phosphorylation at S10 . Hence , cross - talk in plants exists between phosphorylation of H3S10 and methylation , acetylation or phosphorylation of neighbouring amino acid residues . AtAurora1 undergoes autophosphorylation in vivo regardless of the presence of substrate , and forms dimers in planta . Of the three ATP - competitive Aurora inhibitors tested , Hesperadin was most effective in reducing the in vivo kinase activity of AtAurora1 . Hesperadin consistently inhibited histone H3S10 phosphorylation during mitosis in Arabidopsis cells , but did not affect other H3 post - translational modifications , suggesting a specific inhibition of AtAurora in vivo . Inactivation of AtAurora also caused lagging chromosomes in a number of anaphase cells , but , unlike the situation in mammalian cells , Hesperadin did not influence the microtubule dynamics in dividing cells .