Proteolytic maturation of the turnip-yellow-mosaic-virus polyprotein coded in vitro occurs by internal catalysis

Area of Science:

• Molecular Biology
• Virology
• Biochemistry

Background:

• Turnip yellow mosaic virus (TYMV) genomic RNA translation yields high-molecular-weight proteins.
• The larger protein (195,000 Mr) undergoes post-translational cleavage.
• Understanding this cleavage is crucial for viral replication and protein maturation.

Purpose of the Study:

• To investigate the mechanism of post-translational cleavage of the 195,000-Mr protein from TYMV.
• To elucidate the formation of primary cleavage products (120,000 Mr and 78,000 Mr).

Main Methods:

• In vitro translation of TYMV genomic RNA.
• Analysis of protein cleavage products using molecular weight determination.
• Dilution experiments to assess reaction kinetics.

Main Results:

• TYMV genomic RNA translated into two major high-molecular-weight proteins in vitro.
• The 195,000-Mr protein was observed to undergo post-translational cleavage.
• Cleavage occurred at a rate partially insensitive to protein dilution, indicating an intramolecular process.

Conclusions:

• The post-translational cleavage of the 195,000-Mr protein from TYMV likely proceeds via an intramolecular mechanism.
• This finding provides insight into the proteolytic maturation of viral proteins.