DNA double-strand breaks (DSBs) are highly cytotoxic DNA lesions that trigger non-proteolytic ubiquitylation of adjacent chromatin areas to generate binding sites for DNA repair factors. This depends on the sequential actions of the E3 ubiquitin ligases RNF8 and RNF168 (refs 1-6), and UBC13 (also known as UBE2N), an E2 ubiquitin-conjugating enzyme that… (More)
During DNA damage response, the RING E3 ligase RNF168 ubiquitinates nucleosomal H2A at K13-15. Here we show that the ubiquitination reaction is regulated by its substrate. We define a region on the RING domain important for target recognition and identify the H2A/H2B dimer as the minimal substrate to confer lysine specificity to the RNF168 reaction.… (More)
DNA mismatch repair corrects errors that have escaped polymerase proofreading, increasing replication fidelity 100- to 1000-fold in organisms ranging from bacteria to humans. The MutL protein plays a central role in mismatch repair by coordinating multiple protein-protein interactions that signal strand removal upon mismatch recognition by MutS. Here we… (More)
Two studies in this issue, Kristariyanto et al. (2015) and Michel et al. (2015), describe innovative ways to produce large quantities of atypical K29 and K33 ubiquitin chains and report structures and mechanisms of chain-specific recognition.