The adenovirus protease is activated by a virus-coded disulphide-linked peptide

Area of Science:

• Virology
• Molecular Biology
• Biochemistry

Background:

• Adenoviruses encode a protease crucial for viral infectivity.
• The precise mechanism of adenovirus protease activation remained unclear.

Purpose of the Study:

• To elucidate the activation mechanism of adenovirus protease.
• To identify the viral component responsible for protease activation.

Main Methods:

• In vitro complementation assays using recombinant adenovirus protease.
• Characterization of protease activity with peptide and protein substrates.
• Identification and synthesis of the activating viral peptide (pVI-derived).
• Analysis of cysteine's role and dimer requirement using synthetic peptides.

Main Results:

• Recombinant adenovirus protease showed activity only when reconstituted with a viral component.
• The activating component was identified as a peptide derived from the adenovirus protein pVI (GVQSLKRRRCF).
• Cysteine was essential for activity, and a disulphide-linked dimer form of the peptide was required.
• Activity was reconstituted by a component of adenovirus virions, which was identified as GVQSLKRRRCF, a peptide derived from the virus protein pVI.

Conclusions:

• Adenovirus protease is proposed to be a cysteine protease.
• Activation involves a novel thiol-disulphide interchange mechanism mediated by the pVI-derived peptide.
• This mechanism exposes the active site cysteine, representing a new strategy for controlling viral protease activity during maturation.