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Publication Abstract from PubMed

DNA polymerase alpha-primase (Pol-prim) plays an essential role in eukaryotic DNA replication, initiating synthesis of the leading strand and of each Okazaki fragment on the lagging strand. Pol-prim is composed of a primase heterodimer that synthesizes an RNA primer, a DNA polymerase subunit that extends the primer, and a regulatory B-subunit (p68) without apparent enzymatic activity. Pol-prim is thought to interact with eukaryotic replicative helicases, forming a dynamic multiprotein assembly that displays primosome activity. At least three subunits of Pol-prim interact physically with the hexameric replicative helicase SV40 large T antigen, constituting a simple primosome that is active in vitro. However, structural understanding of these interactions and their role in viral chromatin replication in vivo remains incomplete. Here, we report the detailed large T antigen-p68 interface, as revealed in a co-crystal structure and validated by site-directed mutagenesis, and we demonstrate its functional importance in activating the SV40 primosome in cell-free reactions with purified Pol-prim, as well as in monkey cells in vivo.

Structural basis for the interaction of a hexameric replicative helicase with the regulatory subunit of human DNA polymerase alpha-primase.,Zhou B, Arnett DR, Yu X, Brewster A, Sowd GA, Xie CL, Vila S, Gai D, Fanning E, Chen XS J Biol Chem. 2012 Aug 3;287(32):26854-66. doi: 10.1074/jbc.M112.363655. Epub 2012, Jun 14. PMID:22700977^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.