Establishment of a promoter based chromatin architecture on recently replicated DNA can accommodate variable inter-nucleosome spacing.. Chromatin Dynamics During DNA Replication

Nucleosomes, the fundamental subunits of eukaryotic chromatin, are organised with respect to transcriptional start sites. A major challenge to the persistence of this organisation is the disassembly of nucleosomes during DNA replication. Here we use complimentary approaches to map the locations of nucleosomes on recently replicated DNA. We find that nucleosomes are substantially realigned with promoters during the minutes following DNA replication. As a result, the nucleosomal landscape is largely re-established before newly replicated chromosomes are partitioned into daughter cells and can serve as a platform for the reestablishment of gene expression programmes. When the supply of nascent histones is disrupted through mutation of the chaperone Caf1, a promoter based architecture is generated, but with increased inter-nucleosomal spacing. This indicates that the chromatin remodelling enzymes responsible for spacing nucleosomes are capable of organising nucleosomes with a range of different linker DNA lengths.