2c22

File:2c22.gif

spinqualitylabelsall models 2c22, resolution 2.56Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

EFFICIENT AND HIGH FIDELITY INCORPORATION OF DCTP OPPOSITE 7,8-DIHYDRO-8-OXODEOXYGUANOSINE BY SULFOLOBUS SOLFATARICUS DNA POLYMERASE DPO4

OverviewOverview

DNA polymerases insert dATP opposite the oxidative damage product 7,8-dihydro-8-oxodeoxyguanosine (8-oxoG) instead of dCTP, to the extent of >90% with some polymerases. Steady-state kinetics with the Y-family Sulfolobus solfataricus DNA polymerase IV (Dpo4) showed 90-fold higher incorporation efficiency of dCTP > dATP opposite 8-oxoG and 4-fold higher efficiency of extension beyond an 8-oxoG:C pair than an 8-oxoG:A pair. The catalytic efficiency for these events (with dCTP or C) was similar for G and 8-oxoG templates. Mass spectral analysis of extended DNA primers showed >/=95% incorporation of dCTP > dATP opposite 8-oxoG. Pre-steady-state kinetics showed faster rates of dCTP incorporation opposite 8-oxoG than G. The measured K(d)(,dCTP) was 15-fold lower for an oligonucleotide containing 8-oxoG than with G. Extension beyond an 8-oxoG:C pair was similar to G:C and faster than for an 8-oxoG:A pair, in contrast to other polymerases. The E(a) for dCTP insertion opposite 8-oxoG was lower than for opposite G. Crystal structures of Dpo4 complexes with oligonucleotides were solved with C, A, and G nucleoside triphosphates placed opposite 8-oxoG. With ddCTP, dCTP, and dATP the phosphodiester bonds were formed even in the presence of Ca(2+). The 8-oxoG:C pair showed classic Watson-Crick geometry; the 8-oxoG:A pair was in the syn:anti configuration, with the A hybridized in a Hoogsteen pair with 8-oxoG. With dGTP placed opposite 8-oxoG, pairing was not to the 8-oxoG but to the 5' C (and in classic Watson-Crick geometry), consistent with the low frequency of this frameshift event observed in the catalytic assays.

About this StructureAbout this Structure

2C22 is a Single protein structure of sequence from Sulfolobus solfataricus with and as ligands. Active as DNA-directed DNA polymerase, with EC number 2.7.7.7 Known structural/functional Site: . Full crystallographic information is available from OCA.

ReferenceReference

Efficient and high fidelity incorporation of dCTP opposite 7,8-dihydro-8-oxodeoxyguanosine by Sulfolobus solfataricus DNA polymerase Dpo4., Zang H, Irimia A, Choi JY, Angel KC, Loukachevitch LV, Egli M, Guengerich FP, J Biol Chem. 2006 Jan 27;281(4):2358-72. Epub 2005 Nov 22. PMID:16306039

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