Adenovirus Type 2 Endoprotease: Isoforms and Redox Effects

• Published in: Journal of general virology Vol. 77; no. 9; pp. 2201 - 2207
• Main Authors: Keyvani-Amineh, Hossein, Diouri, Mounir, Tihanyi, Karoly, Weber, Joseph M
• Format: Journal Article
• Language: English
• Published: England Soc General Microbiol 01-09-1996
• Subjects: Adenoviruses, Human - enzymology; Cysteine Endopeptidases - drug effects; Cysteine Endopeptidases - metabolism; Diamines - pharmacology; Disulfides; Humans; Isoenzymes - drug effects; Isoenzymes - metabolism; Oxidants - pharmacology; Oxidation-Reduction
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/0022-1317-77-9-2201

Department of Microbiology, Faculty of Medicine, University of Sherbrooke, Quebec, Canada J1H 5N4
Author for correspondence: Joseph M, Weber. Fax + 1 819 564 5392, e-mail j.weber{at}courrier.usherb.ca
The cysteine protease encoded by adenovirus type 2 contains eight cysteines, some of which are involved in catalysis and enzyme activation. Here we investigated the effects of oxidation, mercaptoethanol, dithiothreitol, diamide and protein disulphide isomerase on wild-type and mutant enzymes. Three isoforms of the enzyme were detected in infected cells and a fourth in preparations of purified recombinant enzyme. The latter isoform was absent in preparations of enzyme mutated at any of the three conserved cysteines, C-104, C-122 and C-126. Enzyme activity could be stimulated by agents other than the authentic activating peptide (pVIc), such as cysteamine, though less efficiently. Diamide at low concentrations stimulated the activity of the ts1 enzyme, but inhibited both ts1 and wild-type enzyme at higher concentrations. Protein disulphide isomerase failed to restore enzyme activity to the oxidized isoform. The present studies incombination with previous results using mutants appeared to rule out amino acids C-67, C-122, C-126 and C-127, leaving the two remaining semi-conserved C-17 and C-40 and the conserved C-104 as potential candidates for binding peptide pVIc.
Present address: EGIS, Biological Laboratories, PO Box 100, H-1475 Budapest 10, Hungary.
Received 19 March 1996;
accepted 14 May 1996.