Genetics

Copying chromatin to ensure identity

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Science  21 Aug 2015:
Vol. 349, Issue 6250, pp. 839-840
DOI: 10.1126/science.349.6250.839-e

Structure of the MCM2 histone binding domain–histones H3–H4 tetramer complex

IMAGE: WAVEBREAKMEDIA/ISTOCK

When cells divide, they must replicate both their DNA sequence and the chromatin state of their genome to maintain their identity. Huang et al. use structural and biochemical analyses to show how a central component of the human DNA replication machinery, the minichromsome maintenance (MCM) helicase, helps chaperone histones (proteins that package DNA into structures called nucleosomes) from old nucleosomes disassembled ahead of the replication fork to new ones formed behind the fork. The MCM2 subunit works with another histone chaperone, ASF1, to bind both old and new histones, together with variant histones, such as those from the centromeres. In this way, the cell likely ensures the accurate copying of chromatin as well as DNA.

Nat. Struct. Mol. Biol. 10.1038/nsmb.3055 (2015).

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