Bidentate and tridentate metal-ion coordination states within ternary complexes of RB69 DNA polymerase.

ABSTRACT: Two divalent metal ions are required for primer-extension catalyzed by DNA polymerases. One metal ion brings the 3'-hydroxyl of the primer terminus and the α-phosphorus atom of incoming dNTP together for bond formation so that the catalytically relevant conformation of the triphosphate tail of the dNTP is in an α,β,γ-tridentate coordination complex with the second metal ion required for proper substrate alignment. A probable base selectivity mechanism derived from structural studies on Dpo4 suggests that the inability of mispaired dNTPs to form a substrate-aligned, tridentate coordination complex could effectively cause the mispaired dNTPs to be rejected before catalysis. Nevertheless, we found that mispaired dNTPs can actually form a properly aligned tridentate coordination complex. Howev

SUBMITTER: Xia S 

PROVIDER: S-EPMC3375444 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature