A novel labeling technique reveals a function for histone H2A/H2B dimer tail domains in chromatin assembly in vivo

During S phase in eukaryotes, assembly of chromatin on daughter strands is thought to be coupled to DNA replication. However, conflicting evidence exi sts concerning the role of the highly conserved core histone tail domains i n this process. Here we present a novel in vivo labeling technique that was used to examine the role of the amino-terminal tails of the H2A/H2B dimer in replication-coupled assembly in live cells. Our results show that these domains are dispensable for nuclear import but at least one tail is require d for replication-dependent, active assembly of H2A/H2B dimers into chromat in in vivo.