Reactive serine in human adenovirus hexon polypeptide

Abstract

Affinity labeling with diisopropylfluorophosphate (DFP) is used to study the enzymes associated with human adenovirus type 2 infection. A DFP-labeled 120K polypeptide is constantly found at a late stage of the virus cycle. Biochemical and immunological data indicate that this 120K polypeptide corresponds to the hexon subunit. No detectable enzymatic activity is found associated with native or urea-denatured adenovirus 2 hexon capsomer, and no DFP-labeled components appeared to be incorporated into virus or assembly intermediate particles. DFP reacts with urea-denatured hexon in vitro with an apparent dissociation constant of 5 × 10 -9 M. The occurrence of at least one transient reactive serine residue on the hexon polypeptide subunit and its possible implication in folding and/or assembly of hexon subunits into a hexon trimer is discussed.