Crystal Structure of the Human Pol α B Subunit in Complex with the C-terminal Domain of the Catalytic Subunit

作者：Yoshiaki Suwa, Jianyou Gu, Andrey G. Baranovskiy, Nigar D. Babayeva, Youri I. Pavlov, T.H. Tahirov · 发表于：Journal of Biological Chemistry · 年份：2015 · DOI：10.1074/jbc.m115.649954 · 被引用次数：66 · 研究领域：DNA Repair Mechanisms、Genetic factors in colorectal cancer、Enzyme Structure and Function

In eukaryotic DNA replication, short RNA-DNA hybrid primers synthesized by primase-DNA polymerase α (Prim-Pol α) are needed to start DNA replication by the replicative DNA polymerases, Pol δ and Pol ϵ. The C terminus of the Pol α catalytic subunit (p180 C ) in complex with the B subunit (p70) regulates the RNA priming and DNA polymerizing activities of Prim-Pol α. It tethers Pol α and primase, facilitating RNA primer handover from primase to Pol α. To understand these regulatory mechanisms and to reveal the details of human Pol α organization, we determined the crystal structure of p70 in complex with p180 C . The structured portion of p70 includes a phosphodiesterase (PDE) domain and an oligonucleotide/oligosaccharide binding (OB) domain. The N-terminal domain and the linker connecting it to the PDE domain are disordered in the reported crystal structure. The p180 C adopts an elongated asymmetric saddle shape, with a three-helix bundle in the middle and zinc-binding modules (Zn1 and Zn2) on each side. The extensive p180 C -p70 interactions involve 20 hydrogen bonds and a number of hydrophobic interactions resulting in an extended buried surface of 4080 Å 2 . Importantly, in the structure of the p180 C -p70 complex with full-length p70, the residues from the N-terminal to the OB domain contribute to interactions with p180 C . The comparative structural analysis revealed both the conserved features and the differences between the human and yeast Pol α complexes. Background: DN...