5j29
From Proteopedia
Ternary complex crystal structure of DNA polymerase Beta with A:A mismatch at the primer terminus
Structural highlights
Function[DPOLB_HUMAN] Repair polymerase that plays a key role in base-excision repair. Has 5'-deoxyribose-5-phosphate lyase (dRP lyase) activity that removes the 5' sugar phosphate and also acts as a DNA polymerase that adds one nucleotide to the 3' end of the arising single-nucleotide gap. Conducts 'gap-filling' DNA synthesis in a stepwise distributive fashion rather than in a processive fashion as for other DNA polymerases.[1] [2] [3] [4] Publication Abstract from PubMedHigh-fidelity DNA synthesis requires that polymerases display a strong preference for right nucleotide insertion. When the wrong nucleotide is inserted, the polymerase deters extension from the mismatched DNA terminus. Twenty-three crystallographic structures of DNA polymerase beta with terminal template-primer mismatches were determined as binary DNA and ternary pre-catalytic substrate complexes. These structures indicate that the mismatched termini adopt various distorted conformations that attempt to satisfy stacking and hydrogen-bonding interactions. The binary complex structures indicate an induced strain in the mismatched template nucleotide. Addition of a non-hydrolyzable incoming nucleotide stabilizes the templating nucleotide with concomitant strain in the primer terminus. Several dead-end ternary complex structures suggest that DNA synthesis might occur as the enzyme transitions from an open to a closed complex. The structures are consistent with an induced-fit mechanism where a mismatched terminus is misaligned relative to the correct incoming nucleotide to deter or delay further DNA synthesis. Structures of DNA Polymerase Mispaired DNA Termini Transitioning to Pre-catalytic Complexes Support an Induced-Fit Fidelity Mechanism.,Batra VK, Beard WA, Pedersen LC, Wilson SH Structure. 2016 Sep 13. pii: S0969-2126(16)30238-6. doi:, 10.1016/j.str.2016.08.006. PMID:27642161[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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