A Replicator-Specific Binding Protein Essential For Initiation of DNA Replication in Mammalian Cells

Monday, September 22, 2014 — Poster Session II
4:00 p.m. – 6:00 p.m.	FAES Academic Center	NCI	CHROM-3

* FARE Award Winner

Authors

• Y. Zhang
• L. Huang
• H.Q. Fu
• C.M. Lin
• O.K. Smith
• K. Utani
• M.I. Aladjem

Abstract

Mammalian chromosome replication starts from distinct sites, but the principles governing initiation site selection are unclear because proteins essential for DNA replication do not exhibit sequence-specific DNA binding. To better understand sequence-specific replication initiation, we have sought to identify and characterize proteins that bind an essential region of the replicator at the human beta globin locus. We have identified a replication initiation determinant (Rep-ID, also called DCAF14/PHIP) protein that formed a sequence specific complex with the replicator. Rep-ID binding sites frequently colocalize with replication initiation events genome wide. Rep-ID protein levels are cell cycle regulated. As a member of the DDB1- and CUL4-associated factor family, Rep-ID interacts with DDB1, Cul4B and CDT1. In K562 cells, in which the beta-globin locus replicates early, Rep-ID binding to the replicator was restricted to the G1- and early S-phase of the cell cycle and Rep-ID participated in an essential distal interaction between the replicator and the locus control region. Rep-ID deficiency results in slow cell proliferation, reduced frequency of replication initiation events, increased replication fork stalling and accumulation of CDT1 on chromatin. These observations suggest that Rep-ID may play multiple roles during the DNA replication process, functioning at specific categories of replication origins.

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