T. Schultheiss et al., POLYPROTEIN PROCESSING IN ECHOVIRUS-22 - A FIRST ASSESSMENT, Biochemical and biophysical research communications, 217(3), 1995, pp. 1120-1127
The major steps of the polyprotein processing of Echovirus 22 (EV22),
a highly unusual member of the picornavirus family, have been characte
rized for the first time by employing in vitro assay systems. Cell-fre
e expression of a P1-2ABC precursor as well as VP1-2A yielded autoprot
eolytically inactive proteins, suggesting that the 2A region of the EV
22 polyprotein does not contain a proteolytic activity. The intra- and
intermolecular cleavage specificity of proteinase 3C, the major prote
olytic enzyme in picornaviruses, was studied by expressing the enzyme
of EV22 in a bacterial system as well as in the framework of precursor
molecules generated by in vitro transcription/translation in a cell-f
ree system. A VP1-2A precursor could very efficiently be cleaved in tt
ans by the recombinant 3C, whereas the junction between P2 and P3 rem
ained uncleaved. Expression of the complete P3-region in the cell-free
system led to the autocatalytic release of large amounts of p22, a pr
otein of the predicted molecular weight of the EV22 proteinase 3C that
nas recognized by an antibody raised against the recombinant enzyme.
(C) 1995 Academic Press, Inc.