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Forced retroevolution of an RNA bacteriophage
N Licis1, Z Balklava, J Van Duin
1Biomedical Research and Study Centre, University of Latvia, Ratsupites 1, Riga, LV 1067, Latvia.
Virology
|June 22, 2000
Summary
The operator hairpin in MS2 bacteriophage, crucial for replication, was found to be dispensable. Evolution favored deletions, demonstrating RNA viruses can revert to attenuated forms.
Area of Science:
- Molecular Biology
- Virology
- Evolutionary Biology
Background:
- The MS2 bacteriophage operator hairpin regulates translation initiation and capsid formation.
- It contains overlapping signals for coat protein and ribosome binding, inhibiting translation.
Purpose of the Study:
- To assess the importance of the MS2 bacteriophage operator hairpin structure.
- To observe evolutionary adaptations in mutant phages under selective pressure.
Main Methods:
- Partial randomization of the operator hairpin sequence.
- Passaging of mutant phages to observe evolutionary changes.
- Analysis of revertant phage activities and genetic makeup.
Main Results:
- Most operator reconstructions failed, yielding imperfect functional mimics.
- Mutants with double nonsense codons evolved by deleting the operator entirely.
- Revertants showed activities ranging from 1% to 20% of wild-type MS2 bacteriophage.
Conclusions:
- The MS2 bacteriophage operator hairpin is dispensable for phage viability.
- RNA viruses can evolve towards attenuated forms by simplifying genetic elements.
- This study offers insights into viral evolution and regulatory element plasticity.