Response of human DNA polymerase iota to DNA lesions.
Lesion bypass is an important mechanism to overcome replication blockage by DNA damage. Translesion synthesis requires a DNA polymerase (Pol). Human Pol iota encoded by the RAD30B gene is a recently identified DNA polymerase that shares sequence similarity to Pol eta. To investigate whether human Pol iota plays a role in lesion bypass we examined the response of this polymerase to several types of DNA damage in vitro. Surprisingly, 8-oxoguanine significantly blocked human Pol iota. Nevertheless, translesion DNA synthesis opposite 8-oxoguanine was observed with increasing concentrations of purified human Pol iota, resulting in predominant C and less frequent A incorporation opposite the lesion. Opposite a template abasic site human Pol iota efficiently incorporated a G, less frequently a T and even less frequently an A. Opposite an AAF-adducted guanine, human Pol iota was able to incorporate predominantly a C. In both cases, however, further DNA synthesis was not observed. Purified human Pol iota responded to a template TT (6-4) photoproduct by inserting predominantly an A opposite the 3' T of the lesion before aborting DNA synthesis. In contrast, human Pol iota was largely unresponsive to a template TT cis-syn cyclobutane dimer. These results suggest a role for human Pol iota in DNA lesion bypass.
Zhang
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Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA and Department of Chemistry, Washington University, St Louis, MO 63130, USA.
Yuan
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F
Wu
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Taylor
J S
JS
Wang
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Z
D000099:Acetoxyacetylaminofluorene / Q000378:metabolism; D001483:Base Sequence; D004247:DNA / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D004249:DNA Damage / Q000235:genetics* / Q000528:radiation effects; D004261:DNA Replication / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D006801:Humans; D011740:Pyrimidine Dimers / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D013379:Substrate Specificity; D013698:Templates, Genetic; D014466:Ultraviolet Rays; D000094769:DNA Polymerase iota
D011740:Pyrimidine Dimers; C024829:8-hydroxyguanine; D006147:Guanine; D000099:Acetoxyacetylaminofluorene; D004247:DNA; D004259:DNA-Directed DNA Polymerase; D000094769:DNA Polymerase iota; C000722070:POLI protein, human