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The two capsid proteins of maize rayado fino virus contain common peptide sequences
Abstract:
Virions of maize rayado fino virus (MRFV) were purified and two major capsid proteins (ca. Mr 29,000 and 22,000) were resolved by SDS-PAGE. When the two major capsid proteins were isolated from gels and compared by one-dimensional peptide mapping after digestion with Staphylococcus aureus V-8 protease, indistinguishable peptide maps were obtained, suggesting that these two proteins contain common peptide sequences. Some preparations also showed minor protein components that were intermediate between the Mr 22,000 and Mr 29,000 capsid proteins. One of the minor proteins, ca. Mr 27,000, gave a peptide map indistinguishable from the major capsid proteins. In vitro ageing of partially purified preparations or virion treatment with proteolytic enzymes failed to show conversion of the Mr 29,000 protein to a Mr 22,000. Protease inhibitors added to the buffers used for virion purification did not affect the apparent 1:3 ratio of 29,000 to 22,000 proteins in the purified preparations.
Insights
Maize rayado fino virus (MRFV) capsid proteins of 29,000 and 22,000 molecular weights share common peptide sequences. This suggests they are related, but conversion between forms was not observed during purification.
Area of Science:
- Plant Virology
- Molecular Biology
- Protein Chemistry
Background:
- Maize rayado fino virus (MRFV) is a significant pathogen affecting maize crops.
- Understanding the virus's structural proteins is crucial for developing control strategies.
- Capsid proteins play a key role in viral structure and assembly.
Purpose of the Study:
- To characterize the major capsid proteins of Maize rayado fino virus (MRFV).
- To investigate the relationship between the different molecular weight capsid protein forms.
- To explore potential post-translational modifications or degradation pathways.
Main Methods:
- Purification of MRFV virions.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein separation.
- One-dimensional peptide mapping using Staphylococcus aureus V-8 protease.
Main Results:
- Two major capsid proteins of approximately 29,000 and 22,000 molecular weights were identified.
- Indistinguishable peptide maps were obtained for both major capsid proteins, indicating shared sequences.
- Minor protein components, including a 27,000 molecular weight protein, also showed similar peptide maps.
- No evidence of conversion from the 29,000 to the 22,000 protein was observed in vitro.
- Protease inhibitors did not alter the observed 1:3 ratio of 29,000 to 22,000 proteins.
Conclusions:
- The major capsid proteins of MRFV share common peptide sequences, suggesting a common origin or precursor.
- The observed molecular weight differences are unlikely due to simple proteolytic cleavage during purification.
- Further research is needed to elucidate the exact nature and origin of the different capsid protein forms.