Molecular Determinants and Consequences of Specificity in Histone 2A Ubiquitination: Moleculaire determinanten en gevolgen van specificiteit bij de ubiquitinatie van histone 2A

textabstractSpecific ubiquitination of histones H2A is a crucial decision making point in the response to DNA damage. This thesis analysis the role of three distinct groups of lysines on H2A that are specifically ubiquitinated by three different E3 ligases, RING1b/BMI1, BRCA1/BARD1 and RNF168. The mechanistic basics underlying this specificity are discussed. The work describes how specific ubiquitination is employed to guide repair pathway choice between homologous recombination and non-homologous end joining. It shows that USP48, a deubiquitinating enzyme specific for the BRCA1 ubiquitination site, guides repair pathway choice by determining the extent of DNA end resection. Analysis of the E3 ligase RNF168 shows how specific interaction of the E3 with the nucleosomal acidic patch defines site-specificity. Furthermore, a general framework for structural analysis of E3-E2-Substrate complexes is presented