NEW STIMULATION LIGAND OF THE ADENOVIRUS-2 PROTEASE

The catalytic activity of the adenovirus cysteine peptidase is increas ed by a specific 11-amino-acid peptide adduct (GVQSLKRRRCF, referred t o as pVlc). To identify additional peptides which might bind and alter the activity of the protease, a cysteine-constrained random peptide p hage library was screened. Oi 29 different phages which were isolated, 7 contained the consensus sequence VEGGS. Despite a superficial simil arity to the substrate cleavage site of the protease, the peptide was not digested by the enzyme. VEGGS and pVlc altered protease activity s imilarly without sharing sequence similarity. to similar degrees, pVlc and VEGGS (a) stimulated the activity of the recombinant protease, (b ) had no effect on viral protease, (c) increased the fluorescence emis sion oi tryptophan residues in the protease, suggesting a conformation al change, and (d) inhibited wt virus infection, but rescued rst infec tion at the nonpermissive temperature. The experiments also suggest th at once the protease has been stimulated by one peptide, the other pep tide has no further activity on the recombinant adenovirus cysteine pr otease, suggesting that the two peptides bring about the same change o n the protease via different binding sites. (C) 1996 Academic Press, I nc.