CLONING, EXPRESSION, AND CHARACTERIZATION OF THE PROTEINASE FROM HUMAN HERPESVIRUS-6

After the U53 gene encoding the proteinase from human herpesvirus 6 (H HV-6) was sequenced, it was expressed in Escherichia coli, and the act ivity of the purified, recombinant HHV-6 proteinase was characterized quantitatively by using synthetic peptide substrates mimicking the rel ease and maturation cleavage sites in the polyprotein precursors of HH V-6, human cytomegalovirus (CMV), murine CMV, and Epstein-Barr virus. Despite sharing 40% identity with other betaherpesvirus proteinases su ch as human CMV proteinase, the one-chain HHV-6 enzyme was distinguish ed from these two-chain proteinases by the absence of an internal auto catalytic cleavage site.