THE ADENOVIRUS PROTEASE IS ACTIVATED BY A VIRUS-CODED DISULFIDE-LINKED PEPTIDE

In common with many other viruses, adenoviruses code for a protease essential for the development of infectivity. Recombinant adenovirus protease was active in crude in vitro complementation assays but was inactive with peptide or purified protein substrates. Activity was reconstituted by a component of adenovirus virions, which was identified as GVQSLKRRRCF, a peptide derived from the virus protein pVI. Synthetic peptides were used to demonstrate that the cysteine is essential and that the disulphide-linked dimer is required for activity. It is proposed that the adenovirus protease is a cysteine protease and that its activation by the peptide involves thiol-disulphide interchange, which serves to expose the active site cysteine. This represents a novel strategy for controlling the activity of a protease that is required for virus maturation.