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Implications of the picornavirus capsid structure for polyprotein processing.
Summary
Picornavirus maturation involves sequential protein cleavages. The final step, VP0 cleavage, may use an autocatalytic serine protease mechanism with viral RNA assistance.
Area of Science:
- Virology
- Structural Biology
- Biochemistry
Background:
- Mature picornaviral proteins result from precursor polyprotein cleavage.
- These posttranslational modifications are crucial for controlling virus functions.
Purpose of the Study:
- To investigate the structural and mechanistic aspects of picornavirus polyprotein processing.
- To understand the final maturation step involving the VP0 peptide.
Main Methods:
- Analysis of three-dimensional structures of rhinovirus and Mengo virus.
- Inference of precursor polypeptide chain arrangement and cleavage site flexibility.
Main Results:
- Cleavage sites within the precursor are located in flexible regions.
- The final VP0 (peptide 1AB) maturation likely involves an autocatalytic serine protease-type mechanism.
- Viral RNA basic groups may act as proton-abstractors in the cleavage reaction.
Conclusions:
- The structural organization of the precursor protomer is similar to the mature virus.
- The VP0 cleavage mechanism is unusual, potentially involving RNA-mediated catalysis.