Volume 272, Number 9,
Issue of February 28, 1997
pp. 5635-5639
©1997 by The American Society for Biochemistry and Molecular Biology, Inc.
Activation of the Adenovirus Protease Requires Sequence Elements
from Both Ends of the Activating Peptide
(Received for publication, August 5, 1996, and in revised form, November 5, 1996)
Gonçalo
Cabrita
,
Munir
Iqbal
,
Helen
Reddy
and
Graham
Kemp
From the Division of Cell and Molecular Biology, University of St.
Andrews, Irvine Building, North Street,
St. Andrews KY16 9AL, Scotland
The adenovirus protease requires activation by an
11-residue peptide, GVQSLKRRRCF, to achieve maximum proteolytic
activity. Derived from the C terminus of the viral protein pVI, the
activating peptide (pVI-CT) forms a disulfide bond with cysteine 104 of
the protease and causes a conformational change that accompanies the development of proteolytic activity. Results presented here show that
the interaction of pVI-CT with the protease is dependent not only on
the cysteine 10 but also on glycine 1 and valine 2. Removal of these
residues, acetylation of the N-terminal glycine, or mutation of the
valine to alanine or threonine significantly reduces or abolishes
activation. Peptides lacking Gly-1 and Val-2 still form a disulfide
bond with the protease but do not cause a conformational change in the
protease also they are not effective inhibitors of activation as the
interaction is readily reversed by full-length pVI-CT. These results
suggest that pVI-CT causes activation by binding to two distinct
regions of the protease and in doing so stabilizes the catalytic site.
The reversible nature of the activation, suggested by the results
presented here, may well reflect an in vivo regulatory
mechanism.