Herpes simplex virus type 1 recombination: the Uc-DR1 region is required for high-level a-sequence-mediated recombination.
The a sequences of herpes simplex virus type 1 are believed to be the cis sites for inversion events that generate four isomeric forms of the viral genome. Using an assay that measures deletion of a beta-galactosidase gene positioned between two directly repeated sequences in plasmids transiently maintained in Vero cells, we had found that the a sequence is more recombinogenic than another sequence of similar size. To investigate the basis for the enhanced recombination mediated by the a sequence, we examined plasmids containing direct repeats of approximately 350 bp from a variety of sources and with a wide range of G+C content. We observed that all of these plasmids show similar recombination frequencies (3 to 4%) in herpes simplex virus type 1-infected cells. However, recombination between directly repeated a sequences occurs at twice this frequency (6 to 10%). In addition, we find that insertion of a cleavage site for an a-sequence-specific endonuclease into the repeated sequences does not appreciably increase the frequency of recombination, indicating that the presence of endonuclease cleavage sites within the a sequence does not account for its recombinogenicity. Finally, by replacing segments of the a sequence with DNA fragments of similar length, we have determined that only the 95-bp Uc-DR1 segment is indispensable for high-level a-sequence-mediated recombination.
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Department of Biochemistry, Stanford University School of Medicine, California 94305.
Zemelman
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Lehman
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D000818:Animals; D001483:Base Sequence; D004261:DNA Replication / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics; D004720:Endonucleases / Q000235:genetics; D016679:Genome, Viral; D018259:Herpesvirus 1, Human / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D014709:Vero Cells
D004279:DNA, Viral; D004720:Endonucleases