Y. Stram et al., EXPRESSION OF THE HELPER COMPONENT PROTEIN OF POTATO VIRUS-Y (PVY) INESCHERICHIA-COLI - POSSIBLE INVOLVEMENT OF A 3RD PROTEASE, Virus genes, 7(2), 1993, pp. 151-156
Transmission of polyviruses by aphids depends on the presence of a vir
us encoded helper-component protein (HC) that also exhibits protease a
ctivity. HC was expressed in E. coli from two types of clones: a full-
length cDNA clone of PVY and two 5' end clones containing the first th
ree cistrons (3.6-3.7 kbp). The clones derived from the 5' end of PVY
expressed HC of the size of the mature component. Other proteins react
ing with antibodies to HC were also observed, and their sizes correspo
nded with those of expected intermediates resulting from partial prote
ase cleavage of the three-cistron polyprotein. On the other hand, the
only detectable HC-related product of the full-length clone was a matu
re-size HC. The presence of a third PVY protease among the first three
cistrons is therefore suggested.