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SV40 recombinants carrying a d(CT.GA)22 sequence show increased genomic instability
J Bernúes1, R Beltrán, F Azorín
1Grupo de Química Macromolecular, Centro de Investigación y Desarrollo CSIC, Barcelona, Spain.
Gene
|December 15, 1991
Summary
Repetitive DNA sequences, like d(CT.GA)22, can destabilize viral genomes. Introducing this sequence into SV40 DNA increased viral recombination and produced defective viruses, suggesting a role in genetic instability.
Area of Science:
- Genetics
- Molecular Biology
- Virology
Background:
- Repetitive d(CT.GA)n sequences are common in eukaryotic DNA, often found in recombination sites or promoter regions.
- These sequences are known for their propensity to form triple-stranded structures.
Purpose of the Study:
- To investigate the biological function of repetitive d(CT.GA)n sequences.
- To analyze the genomic stability of SV40 recombinants carrying a synthetic d(CT.GA)22 sequence.
Main Methods:
- Insertion of a synthetic d(CT.GA)22 sequence into the SV40 genome at the HpaII site.
- Serial passage of SV40 recombinants (SV/CT22 viruses) in permissive CV1 cells.
- Analysis of genomic stability and characterization of viral variants.
Main Results:
- SV/CT22 recombinants showed increased production of defective viruses upon serial passage.
- Viral variants likely arose through recombination between and within viral molecules.
- One variant (SV/X) with a replicative advantage, featuring a tandem duplication of an early SV40 DNA fragment including the origin of replication (ori), became dominant.
Conclusions:
- The repetitive d(CT.GA)22 sequence enhances the rate of recombination in the SV40 genome.
- This enhancement is likely due to the sequence's ability to form triple-stranded structures.
- The emergence of diverse variants suggests complex mechanisms of genome instability induced by repetitive sequences.