Requirement of mammalian DNA polymerase-beta in base-excision repair.
Synthesis of DNA by DNA polymerase-beta is distributive on single-stranded DNA templates, but short DNA gaps with a 5' PO4 in the gap are filled processively to completion. In vitro studies have suggested a role of beta-polymerase in different types of DNA repair. However, the significance of these studies to the in vivo role of beta-polymerase has remained unclear. Because genetic studies are essential for determining the physiological role of a gene, we established embryonic fibroblast cell lines homozygous for a deletion mutation in the gene encoding DNA polymerase-beta. Extracts from these cell lines were found to be defective in uracil-initiated base-excision repair. The beta-polymerase-deleted cells are normal in viability and growth characteristics, although they exhibit increased sensitivity to monofunctional DNA-alkylating agents, but not to other DNA-damaging agents. Both the deficiency in base-excision repair and hypersensitivity to DNA-alkylating agents are rescued following stable transfection with a wild-type beta-polymerase minitransgene. These studies demonstrate that beta-polymerase functions specifically in base-excision repair in vivo.
Sealy Center for Molecular Science, University of Texas Medical Branch, Galveston 77555-1068, USA.
R W
RW
Sobol
J K
JK
Horton
R
R
Kühn
H
H
Gu
R K
RK
Singhal
R
R
Prasad
K
K
Rajewsky
S H
SH
Wilson
D000818:Animals; D002455:Cell Division; D002460:Cell Line; D002461:Cell Line, Transformed; D002470:Cell Survival; D004256:DNA Polymerase I / Q000378:metabolism*; D004260:DNA Repair; D017353:Gene Deletion; D005816:Genetic Complementation Test; D018095:Germ-Line Mutation; D051379:Mice; D008822:Mice, Transgenic; D010641:Phenotype; D015183:Restriction Mapping
D004256:DNA Polymerase I