Direct repeats of the herpes simplex virus a sequence promote nonconservative homologous recombination that is not dependent on XPF/ERCC4.
We have examined mechanisms of recombination in mammalian cells infected with herpes simplex virus type 1 (HSV-1). Amplification of plasmids containing a viral origin of replication, oriS, in cells superinfected with HSV-1 revealed that linear DNA could be efficiently converted to templates for replication. Two distinct pathways were observed: imprecise end joining and nonconservative homologous recombination. We noted that direct repeats of the viral a sequence promoted efficient nonconservative homologous recombination in BHK cells as well as human repair-proficient 1BR.3N cells and xeroderma pigmentosum group F (XP-F) cells. The reaction gave rise to functional a sequences supporting the formation of defective viruses. It did not seem to proceed by single-strand annealing since it occurred in the absence of XPF/ERCC4, the mammalian homolog of the Rad1 endonuclease from Saccharomyces cerevisiae. In contrast, direct repeats of a 161-bp nonviral sequence did not take part in nonconservative homologous recombination in XP-F cells. Our results suggest that homologous recombination may be involved in the circularization of viral genomes. Furthermore, they demonstrate that amplification of recombination products supported by HSV-1 allows a direct examination of pathways for double-strand-break repair in human cells.
Yao
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Department of Medical Biochemistry, University of Göteborg, Sweden.
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Elias
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D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D004261:DNA Replication; D004270:DNA, Circular; D004279:DNA, Viral; D004268:DNA-Binding Proteins / Q000502:physiology*; D003673:Defective Viruses; D005814:Genes, Viral; D018259:Herpesvirus 1, Human / Q000235:genetics* / Q000502:physiology; D006801:Humans; D010957:Plasmids; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D018741:Replication Origin; D014779:Virus Replication
D004270:DNA, Circular; D004279:DNA, Viral; D004268:DNA-Binding Proteins; C095888:xeroderma pigmentosum group F protein