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Interference with viral infection by defective RNA replicase
1Department of Molecular Biology, School of Medicine, Keio University, Tokyo, Japan.
Journal of Virology
|December 1, 1987
Summary
Altering a key Glycine residue in the Q beta phage replicase conserved segment significantly inhibits phage proliferation by suppressing RNA synthesis. This suggests specific interference with wild-type and related phage infections.
Area of Science:
- Molecular Biology
- Virology
- Enzymology
Background:
- RNA-dependent RNA and DNA polymerases share a conserved Tyr-X-Asp-Asp motif.
- This motif is crucial for polymerase function.
Purpose of the Study:
- To investigate the function of the conserved Tyr-Gly-Asp-Asp segment in Q beta phage replicase.
- To determine the in vivo effects of altering the Glycine residue at position 357.
Main Methods:
- Site-directed mutagenesis was used to substitute Glycine-357 with Alanine, Serine, Proline, Methionine, or Valine in the Q beta replicase.
- Replicase activity and phage proliferation were examined in vivo.
Main Results:
- Mutations at Glycine-357 abolished replicase activity and severely inhibited Q beta and SP phage proliferation.
- These altered replicases suppressed phage RNA synthesis.
- Substitution at Glycine-390 had a minor inhibitory effect despite loss of replicase activity.
Conclusions:
- The conserved Tyr-Gly-Asp-Asp segment is critical for Q beta phage replicase function.
- Altered replicases at this conserved segment specifically interfere with wild-type and related phage infections.
- This provides insights into phage-host interactions and potential antiviral strategies.