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RNA structural requirements for stability and minus-strand synthesis in the dsRNA bacteriophage phi 6
1Department of Microbiology, Public Health Research Institute, New York, New York 10016.
Virology
|July 1, 1994
Summary
Bacteriophage phi 6 RNA genome segments require intact 3' ends for minus-strand synthesis. Deletions in this region impair synthesis but can be repaired by recombination, making defective segments highly recombinogenic.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Bacteriophage phi 6 possesses a three-segment double-stranded RNA genome (L, M, S).
- Procapsids package plus-strand RNA transcripts with intact 5' regions.
- Minus-strand synthesis necessitates packaging of all three segments and intact 3' ends.
Purpose of the Study:
- To investigate the role of conserved 3' end structures in bacteriophage phi 6 minus-strand RNA synthesis.
- To determine the impact of deletions in the 3' conserved region on replication and recombination.
Main Methods:
- Site-directed mutagenesis to create deletions in the 3' conserved region of phi 6 RNA segments.
- Assays for minus-strand RNA synthesis in vitro.
- Analysis of heterologous recombination between defective and intact RNA segments.
Main Results:
- Progressive deletions in the 3' conserved region led to a gradual loss of minus-strand synthesis capability.
- Defective 3' ends could be functionally restored through heterologous recombination with other segments.
- Segments with minor deletions in the conserved region, despite supporting normal minus-strand synthesis, exhibited high recombinogenicity.
Conclusions:
- The conserved 3' end structures are crucial, but not solely essential, for bacteriophage phi 6 minus-strand RNA synthesis.
- Heterologous recombination plays a significant role in maintaining genome integrity and potentially in the evolution of bacteriophage phi 6.