Nucleic Acids Research Advance Access originally published online on February 2, 2009
Nucleic Acids Research 2009 37(6):1868-1877; doi:10.1093/nar/gkp035
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Nucleic Acids Research, 2009, Vol. 37, No. 6 1868-1877
© 2009 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Nucleic Acid Enzymes |
Human DNA polymerase
possesses 5'-dRP lyase activity and functions in single-nucleotide base excision repair in vitro
1Laboratory of Structural Biology and 2Laboratory of Molecular Genetics, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
*To whom correspondence should be addressed. Tel: +1 919 541 3201; Fax: +1 919 541 3592; Email: wilson5{at}niehs.nih.gov
Received November 13, 2008. Revised December 26, 2008. Accepted January 11, 2009.
DNA polymerase
(Pol
) is a low-fidelity DNA polymerase that belongs to the family A polymerases and has been proposed to play a role in somatic hypermutation. Pol
has the ability to conduct translesion DNA synthesis opposite an AP site or thymine glycol, and it was recently proposed to be involved in base excision repair (BER) of DNA damage. Here, we show that Pol
has intrinsic 5'-deoxyribose phosphate (5'-dRP) lyase activity that is involved in single-nucleotide base excision DNA repair (SN-BER). Full-length human Pol
is a
300-kDa polypeptide, but we show here that the 98-kDa C-terminal region of Pol
possesses both DNA polymerase activity and dRP lyase activity and is sufficient to carry out base excision repair in vitro. The 5'-dRP lyase activity is independent of the polymerase activity, in that a polymerase inactive mutant retained full 5'-dRP lyase activity. Domain mapping of the 98-kDa enzyme by limited proteolysis and NaBH4 cross-linking with a BER intermediate revealed that the dRP lyase active site resides in a 24-kDa domain of Pol
. These results are consistent with a role of Pol
in BER.