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2j6s

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Revision as of 13:24, 23 March 2008 by OCA (Talk | contribs)
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Image:2j6s.gif


PDB ID 2j6s

Drag the structure with the mouse to rotate
, resolution 2.50Å
Sites:
Ligands: and
Activity: DNA-directed DNA polymerase, with EC number 2.7.7.7
Coordinates: save as pdb, mmCIF, xml



TERNARY COMPLEX OF SULFOLOBUS SOLFATARICUS DPO4 DNA POLYMERASE, O6-METHYLGUANINE MODIFIED DNA, AND DATP.


Overview

We examined the effect of a single O6-methylguanine (O6-MeG) template residue on catalysis by a model Y family polymerase, Dpo4 from Sulfolobus solfataricus. Mass spectral analysis of Dpo4-catalyzed extension products revealed that the enzyme accurately bypasses O6-MeG, with C being the major product (approximately 70%) and T or A being the minor species (approximately 20% or approximately 10%, respectively), consistent with steady-state kinetic parameters. Transient-state kinetic experiments revealed that kpol, the maximum forward rate constant describing polymerization, for dCTP incorporation opposite O6-MeG was approximately 6-fold slower than observed for unmodified G, and no measurable product was observed for dTTP incorporation in the pre-steady state. The lack of any structural information regarding how O6-MeG paired in a polymerase active site led us to perform x-ray crystallographic studies, which show that "wobble" pairing occurs between C and O6-MeG. A structure containing T opposite O6-MeG was solved, but much of the ribose and pyrimidine base density was disordered, in accordance with a much higher Km,dTTP that drives the difference in efficiency between C and T incorporation. The more stabilized C:O6-MeG pairing reinforces the importance of hydrogen bonding with respect to nucleotide selection within a geometrically tolerant polymerase active site.

About this Structure

2J6S is a Single protein structure of sequence from Sulfolobus solfataricus. Full crystallographic information is available from OCA.

Reference

Sulfolobus solfataricus DNA polymerase Dpo4 is partially inhibited by "wobble" pairing between O6-methylguanine and cytosine, but accurate bypass is preferred., Eoff RL, Irimia A, Egli M, Guengerich FP, J Biol Chem. 2007 Jan 12;282(2):1456-67. Epub 2006 Nov 14. PMID:17105728

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