Published online 16 December 2004
Nucleic Acids Research, Vol. 32 No. 22 © Oxford University Press 2004; all rights reserved
Pa-AGOG, the founding member of a new family of archaeal 8-oxoguanine DNA-glycosylases
Institute of Molecular Cancer Research, University of Zürich, August Forel-Strasse 7, CH-8008 Zürich, Switzerland, 1 Biomolecular Research, Paul Scherrer-Institut, CH-5232 Villigen, Switzerland and 2 Institute of Biochemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
* To whom correspondence should be addressed. Tel: +41 1 634 8910; Fax: +41 1 634 8904; Email: jiricny{at}imr.unizh.ch
Present address: Alessandro A. Sartori, The Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QR, UK
Received October 17, 2004; Revised and Accepted November 23, 2004
Oxidative damage represents a major threat to genomic stability, as the major product of DNA oxidation, 8-oxoguanine (GO), frequently mispairs with adenine during replication. In order to prevent these mutagenic events, organisms have evolved GO-DNA glycosylases that remove this oxidized base from DNA. We were interested to find out how GO is processed in the hyperthermophilic archaeon Pyrobaculum aerophilum, which lives at temperatures around 100°C. To this end, we searched its genome for open reading frames (ORFs) bearing the principal hallmark of GO-DNA glycosylases: a helixhairpinhelix motif and a glycine/proline-rich sequence followed by an absolutely conserved aspartate (HhH-GPD motif). Interestingly, although the P.aerophilum genome encodes three such ORFs, none of these encodes the potent GO-processing activity detected in P.aerophilum extracts. Fractionation of the extracts, followed by analysis of the active fractions by denaturing polyacrylamide gel electrophoresis, showed that the GO-processing enzyme has a molecular size of
30 kDa. Mass spectrometric analysis of proteins in this size range identified several peptides originating from P.aerophilum ORF PAE2237. We now show that PAE2237 encodes AGOG (Archaeal GO-Glycosylase), the founding member of a new family of DNA glycosylases, which can remove GO from single- and double-stranded substrates with great efficiency.