Nucleic Acids Research Advance Access published online on February 14, 2008
Nucleic Acids Research, doi:10.1093/nar/gkn054
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Molecular Biology |
The effect of sequence context on spontaneous Pol
-dependent mutagenesis in Saccharomyces cerevisiae
1Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, 2Graduate Program in Biochemistry, Cell and Developmental Biology and 3Department of Biology, Emory University, Atlanta, GA 30322, USA
*To whom correspondence should be addressed. Tel: +919 681 7273; Fax: +919 684 2790; Email: sue.robertson{at}duke.edu
Received October 2, 2007. Revised January 23, 2008. Accepted January 24, 2008.
The Pol
translesion synthesis (TLS) DNA polymerase is responsible for over 50% of spontaneous mutagenesis and virtually all damage-induced mutagenesis in yeast. We previously demonstrated that reversion of the lys2
A746 –1 frameshift allele detects a novel type of +1 frameshift that is accompanied by one or more base substitutions and depends completely on the activity of Pol. These ‘complex’ frameshifts accumulate at two discrete hotspots (HS1 and HS2) in the absence of nucleotide excision repair, and accumulate at a third location (HS3) in the additional absence of the translesion polymerase Pol
. The current study investigates the sequence requirements for accumulation of Pol-dependent complex frameshifts at these hotspots. We observed that transposing 13 bp of identity from HS1 or HS3 to a new location within LYS2 was sufficient to recapitulate these hotspots. In addition, altering the sequence immediately upstream of HS2 had no effect on the activity of the hotspot. These data support a model in which misincorporation opposite a lesion precedes and facilitates the selected slippage event. Finally, analysis of nonsense mutation revertants indicates that Pol can simultaneously introduce multiple base substitutions in the absence of an accompanying frameshift event.
Present addresses: Amy L. Abdulovic, Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA Brenda K. Minesinger, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors.