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D. Tok Pol

Yanxiang Zhao, David Jeruzalmi, Ismail Moarefi, Lore Leighton, Roger Lasken, John Kuriyan

Crystal structure of an archaebacterial DNA polymerase.
Structure Fold Des 1999 Oct 15;7(10):1189-99

Members of the Pol II family of DNA polymerases are responsible for chromosomal replication in eukaryotes, and carry out highly processive DNA replication when attached to ring-shaped processivity clamps. The DNA polymerase from the archaebacterium Desulfurococcus strain Tok (D. Tok Pol) is a member of the Pol II family that retains catalytic activity at elevated temperatures. In the crystal structure, the central catalytic region of the DNA polymerase is located within the 'palm' subdomain and is strikingly similar in structure to the corresponding regions of Pol I type DNA polymerases. The structural scaffold that surrounds the catalytic core in D. Tok Pol is unrelated in structure to that of Pol I type polymerases. The structure of D. Tok Pol confirms that the modes of binding of the template and extrusion of newly synthesized duplex DNA are likely to be similar in both Pol II and Pol I type DNA polymerases. However, the mechanism by which the newly synthesized product transits in and out of the proofreading exonuclease domain has to be quite different. The N-terminal domain of D. Tok Pol has structural similarity to RNA-binding domains. Sequence alignments suggest that this domain is conserved in the eukaryotic DNA polymerases delta and epsilon, raising the possibility that Pol II family members interact with RNA.

Protein Structure Coordinates (PDB Entry Number 1QQC)

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