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The same mammalian replicon yields distinct recombination products in different cell lines
H K Vu1, L Delbecchi, D Bourgaux-Ramoisy
1Département de microbiologie, Faculté de médecine, Université de Sherbrooke, Quebec, Canada.
Abstract:
We have observed previously that some chimeric replicons inclusive of a partly duplicated polyomavirus (Py) genome yield unit-length Py DNA (P155) at high frequency when transfected into normal or Py-transformed mouse cells. We demonstrate here that one such replicon generates either P155 or illegitimate recombination products in other mouse cells, transformed by simian virus 40. Use of the polymerase chain reaction indicates that each of the illegitimate products carried a different deletion, but that all deletions mapped within a rather well defined portion of the precursor replicon. Thus, these products were organized as if two hotspots for recombination existed in the Py late-coding region, one being located within or near one of the duplicated sequences characteristic of the chimeric replicon. Since this particular hotspot has already been shown to be involved in the generation of P155, the data reported here could indicate that a single recombination mechanism can yield either homologous (P155) or illegitimate products. How the DNA interacts with certain proteins, such as papovavirus large tumor antigen, could explain why one or the other type of product is formed.
Insights
This study shows a single DNA recombination mechanism can produce either homologous or illegitimate products. This occurs in mouse cells with specific viral DNA, influenced by protein interactions.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Chimeric replicons with duplicated polyomavirus (Py) genomes can generate unit-length Py DNA (P155).
- Previous observations showed high P155 yield in normal or Py-transformed mouse cells.
Purpose of the Study:
- To investigate the recombination products of a specific chimeric replicon in simian virus 40-transformed mouse cells.
- To understand the mechanisms underlying homologous versus illegitimate DNA recombination.
Main Methods:
- Transfection of a chimeric replicon into simian virus 40-transformed mouse cells.
- Analysis of recombination products using polymerase chain reaction (PCR).
- Mapping of deletions within the illegitimate recombination products.
Main Results:
- The chimeric replicon generated both P155 and illegitimate recombination products.
- Illegitimate products contained unique deletions mapping to a specific region of the Py genome.
- Two recombination hotspots were identified in the Py late-coding region, one overlapping with duplicated sequences.
Conclusions:
- A single recombination mechanism may produce both homologous (P155) and illegitimate DNA products.
- The outcome of recombination (homologous vs. illegitimate) might depend on DNA-protein interactions, such as with papovavirus large tumor antigen.
- Understanding these mechanisms is crucial for viral DNA replication and genome stability research.