Summary information and primary citation

5kg3; DSSR-derived features in text and JSON formats
replication, transferase-DNA
X-ray (1.7 Å)
Human DNA polymerase eta-DNA ternary complex: reaction first with 1 mm mn2+ for 1800s then with 10 mm mn2+ for 60s
Gao Y, Yang W (2016): "Capture of a third Mg2+ is essential for catalyzing DNA synthesis." Science, 352, 1334-1337. doi: 10.1126/science.aad9633.
It is generally assumed that an enzyme-substrate (ES) complex contains all components necessary for catalysis and that conversion to products occurs by rearrangement of atoms, protons, and electrons. However, we find that DNA synthesis does not occur in a fully assembled DNA polymerase-DNA-deoxynucleoside triphosphate complex with two canonical metal ions bound. Using time-resolved x-ray crystallography, we show that the phosphoryltransfer reaction takes place only after the ES complex captures a third divalent cation that is not coordinated by the enzyme. Binding of the third cation is incompatible with the basal ES complex and requires thermal activation of the ES for entry. It is likely that the third cation provides the ultimate boost over the energy barrier to catalysis of DNA synthesis.

Cartoon-block schematics in six views (download the tarball)

PyMOL session file Download PDB file View in 3Dmol.js