A method for systematic mapping of protein lysine methylation identifies functions for HP1? in DNA damage response.

ABSTRACT: Lysine methylation occurs on both histone and nonhistone proteins. However, our knowledge on the prevalence and function of nonhistone protein methylation is poor. We describe an approach that combines peptide array, bioinformatics, and mass spectrometry to systematically identify lysine methylation sites and map methyllysine-driven protein-protein interactions. Using this approach, we identified a high-confidence and high-resolution interactome of the heterochromatin protein 1? (HP1?) and uncovered, simultaneously, numerous methyllysine sites on nonhistone proteins. We found that HP1? binds to DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and regulates its localization to double-strand breaks (DSBs) during DNA damage response (DDR). Mutation of the methylation sites in DNA-PKcs or depletion of HP1? in cells caused defects in DDR. Furthermore, we showed that the methylation of DNA-PKcs and many other proteins in the HP1? interactome undergoes large changes in response to DNA damage, indicating that Lys methylation is a highly dynamic posttranslational modification.

SUBMITTER: Liu H 

PROVIDER: S-EPMC4032624 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature