title: The C-terminal domain of the DNA polymerase catalytic subunit regulates the primase and polymerase activities of the human DNA polymerase α-primase complex.
abstract: The initiation of DNA synthesis during replication of the human genome is accomplished primarily by the DNA polymerase α-primase complex, which makes the RNA-DNA primers accessible to processive DNA pols. The structural information needed to understand the mechanism of regulation of this complex biochemical reaction is incomplete. The presence of two enzymes in one complex poses the question of how these two enzymes cooperate during priming of DNA synthesis. Yeast two-hybrid and direct pulldown assays revealed that the N-terminal domain of the large subunit of primase (p58N) directly interacts with the C-terminal domain of the catalytic subunit of polα (p180C). We found that a complex of the C-terminal domain of the catalytic subunit of polα with the second subunit (p180C-p70) stimulated primase activity, whereas the whole catalytically active heterodimer of polα (p180ΔN-p70) inhibited RNA synthesis by primase. Conversely, the polα catalytic domain without the C-terminal part (p180ΔN-core) possessed a much higher propensity to extend the RNA primer than the two-subunit polα (p180ΔN-p70), suggesting that p180C and/or p70 are involved in the negative regulation of DNA pol activity. We conclude that the interaction between p180C, p70, and p58 regulates the proper primase and polymerase function. The composition of the template DNA is another important factor determining the activity of the complex. We have found that polα activity strongly depends on the sequence of the template and that homopyrimidine runs create a strong barrier for DNA synthesis by polα.
authors: From the Eppley Institute for Research in Cancer and Allied Diseases, Department of Biochemistry and Molecular Biology, and.
authors: Yinbo
authors: Y
authors: Zhang
authors: From the Eppley Institute for Research in Cancer and Allied Diseases.
authors: Andrey G
authors: AG
authors: Baranovskiy
authors: From the Eppley Institute for Research in Cancer and Allied Diseases, ttahirov@unmc.edu.
authors: Tahir H
authors: TH
authors: Tahirov
authors: From the Eppley Institute for Research in Cancer and Allied Diseases, Department of Biochemistry and Molecular Biology, and Department of Pathology and Microbiology, University of Nebraska Medical Center, Nebraska Medical Center, Omaha, Nebraska 68198-6805 ypavlov@unmc.edu.
authors: Youri I
authors: YI
authors: Pavlov
mesh_terms: D020134:Catalytic Domain; D004256:DNA Polymerase I / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019915:DNA Primase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication; D006801:Humans; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D009097:Multienzyme Complexes; D021122:Protein Subunits; D011994:Recombinant Proteins; D019915:DNA Primase; C116932:DNA polymerase alpha-primase; C525356:PRIM2 protein, human; D004256:DNA Polymerase I
keywords: C-terminal Domain; DNA Polymerase; DNA Polymerase Activity; DNA Polymerase α-Primase; DNA Primase; DNA Replication; DNA Replication Initiation; Primase Activity; Protein-Protein Interaction; RNA