8g9l | pdb_00008g9l

DNA initiation subcomplex of Xenopus laevis DNA polymerase alpha-primase

spinqualitylabelsall models 8g9l, resolution 3.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 8g9l is a 4 chain structure with sequence from Xenopus laevis and Synthetic construct. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.3Å Ligands: DGT, DOC, GTP, MG, SF4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function DPOLA_XENLA Plays an essential role in the initiation of DNA replication. During the S phase of the cell cycle, the DNA polymerase alpha complex (composed of a catalytic subunit POLA1/p180, a regulatory subunit POLA2/p70 and two primase subunits PRIM1/p49 and PRIM2/p58) is recruited to DNA at the replicative forks via direct interactions with MCM10 and WDHD1. The primase subunit of the polymerase alpha complex initiates DNA synthesis by oligomerising short RNA primers on both leading and lagging strands. These primers are initially extended by the polymerase alpha catalytic subunit and subsequently transferred to polymerase delta and polymerase epsilon for processive synthesis on the lagging and leading strand, respectively. The reason this transfer occurs is because the polymerase alpha has limited processivity and lacks intrinsic 3' exonuclease activity for proofreading error, and therefore is not well suited for replicating long complexes (By similarity). Publication Abstract from PubMed The mechanism by which polymerase alpha - primase (polalpha-primase) synthesizes chimeric RNA-DNA primers of defined length and composition, necessary for replication fidelity and genome stability, is unknown. Here, we report cryo-EM structures of polalpha-primase in complex with primed templates representing various stages of DNA synthesis. Our data show how interaction of the primase regulatory subunit with the primer 5'-end facilitates handoff of the primer to polalpha and increases polalpha processivity, thereby regulating both RNA and DNA composition. The structures detail how flexibility within the heterotetramer enables synthesis across two active sites and provide evidence that termination of DNA synthesis is facilitated by reduction of polalpha and primase affinities for the varied conformations along the chimeric primer/template duplex. Together, these findings elucidate a critical catalytic step in replication initiation and provide a comprehensive model for primer synthesis by polalpha-primase. A mechanistic model of primer synthesis from catalytic structures of DNA polymerase alpha-primase.,Mullins EA, Salay LE, Durie CL, Jackman JE, Ohi MD, Chazin WJ, Eichman BF bioRxiv. 2023 Mar 16:2023.03.16.533013. doi: 10.1101/2023.03.16.533013. Preprint. PMID:36993335 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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