3D architecture of DNA Pol alpha reveals the functional core of multi-subunit replicative polymerases.
Eukaryotic DNA replication requires the coordinated activity of the multi-subunit DNA polymerases: Pol alpha, Pol delta and Pol epsilon. The conserved catalytic and regulatory B subunits associate in a constitutive heterodimer that represents the functional core of all three replicative polymerases. Here, we combine X-ray crystallography and electron microscopy (EM) to describe subunit interaction and 3D architecture of heterodimeric yeast Pol alpha. The crystal structure of the C-terminal domain (CTD) of the catalytic subunit bound to the B subunit illustrates a conserved mechanism of accessory factor recruitment by replicative polymerases. The EM reconstructions of Pol alpha reveal a bilobal shape with separate catalytic and regulatory modules. Docking of the B-CTD complex in the EM reconstruction shows that the B subunit is tethered to the polymerase domain through a structured but flexible linker. Our combined findings provide a structural template for the common functional architecture of the three major replicative DNA polymerases.
Klinge
Sebastian
S
Department of Biochemistry, University of Cambridge, Cambridge, UK.
Núñez-Ramírez
Rafael
R
Llorca
Oscar
O
Pellegrini
Luca
L
D000595:Amino Acid Sequence; D000818:Animals; D018360:Crystallography, X-Ray; D004256:DNA Polymerase I / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D016415:Sequence Alignment
D021122:Protein Subunits; D004256:DNA Polymerase I