National Center for
4FXD: Crystal structure of yeast DNA polymerase alpha bound to DNA/RNA
Elife (2013) 2 p.e00482
The DNA Polymerase alpha (Pol alpha)/primase complex initiates DNA synthesis in eukaryotic replication. In the complex, Pol alpha and primase cooperate in the production of RNA-DNA oligonucleotides that prime synthesis of new DNA. Here we report crystal structures of the catalytic core of yeast Pol alpha in unliganded form, bound to an RNA primer/DNA template and extending an RNA primer with deoxynucleotides. We combine the structural analysis with biochemical and computational data to demonstrate that Pol alpha specifically recognizes the A-form RNA/DNA helix and that the ensuing synthesis of B-form DNA terminates primer synthesis. The spontaneous release of the completed RNA-DNA primer by the Pol alpha/primase complex simplifies current models of primer transfer to leading- and lagging strand polymerases. The proposed mechanism of nucleotide polymerization by Pol alpha might contribute to genomic stability by limiting the amount of inaccurate DNA to be corrected at the start of each Okazaki fragment. DOI:http://dx.doi.org/10.7554/eLife.00482.001.