How are histones replicated?
During DNA replication, histone arrangement is perturbed, first to allow progression of DNA polymerase and then during repackaging of the replicated DNA. To study how DNA replication influences the pattern of histone modification, we followed the cell-cycle dynamics of 10 histone marks in budding yeast.
Are nucleosomes involved in DNA replication?
THE NUCLEOSOME AS A CARRIER OF EPIGENETIC INFORMATION In eukaryotic cells, chromatin structures govern a variety of cellular processes including DNA replication and gene transcription.
What happens to nucleosomes after replication?
After the new strand of DNA is synthesized by the polymerase, assembly factors reconstitute old nucleosomes and assemble new nucleosomes behind the replication fork. Because there is a doubling of genetic material during replication, cells require double the amount of the genome packing material, namely, the histones.
How is the nucleosome assembled?
The nucleosome assembly reaction has two steps: histones H3 and H4 are deposited onto DNA as an H3/H4 tetramer in the first step, to form a nucleosome precursor; in the second step, the nucleosome is com- pleted by the association of two H2A/H2B dimers with this precursor.
Are histones inherited?
Parental histones can be inherited close to their starting DNA sequence (i.e., with positional memory). Histone chaperone activities intrinsic to the replisome may mediate positional memory.
How are histones removed during replication?
Model for transfer of epigenetic modifications during DNA replication. Passage of replication machinery completely removes the parental histones and their marks while retaining certain histone modifying enzymes such as the PcG/TrxG complexes still bound to their DNA elements (top panel).
Where does replication independent nucleosome assembly occur?
Nucleosomes are assembled in a DNA replication-coupled (RC) manner following the replication fork during S phase and are assembled onto DNA during gap-repair in response to DNA damage (28, 35). In both cases, nascent DNA is packaged into chromatin.
Are histones removed during DNA replication?
However, during DNA replication, the parental histone proteins are all removed from the DNA during the process of chromatin disassembly, and the chromatin is reassembled onto the two daughter DNA duplexes following DNA replication.
Can chromatin structure be inherited?
Studies in eukaryotes ranging from yeast to mammals indicate that specific chromatin structures can be inherited following DNA replication via mechanisms acting in cis.