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| {{STRUCTURE_2c22| PDB=2c22 | SCENE= }} | | {{STRUCTURE_2c22| PDB=2c22 | SCENE= }} |
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| '''EFFICIENT AND HIGH FIDELITY INCORPORATION OF DCTP OPPOSITE 7,8-DIHYDRO-8-OXODEOXYGUANOSINE BY SULFOLOBUS SOLFATARICUS DNA POLYMERASE DPO4'''
| | ===EFFICIENT AND HIGH FIDELITY INCORPORATION OF DCTP OPPOSITE 7,8-DIHYDRO-8-OXODEOXYGUANOSINE BY SULFOLOBUS SOLFATARICUS DNA POLYMERASE DPO4=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_16306039}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 16306039 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_16306039}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Transferase]] | | [[Category: Transferase]] |
| [[Category: Translesion dna polymerase]] | | [[Category: Translesion dna polymerase]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 21:07:49 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 12:35:08 2008'' |
