TY - JOUR
T1 - The 35-kDa protein from the N-terminus of the potyviral polyprotein functions as a third virus-encoded proteinase
AU - Verchot, Jeanmarie
AU - Koonin, Eugene V.
AU - Carrington, James C.
N1 - Funding Information:
The authors wish to thank Kerri Braden and Chan-Seok Oh for assistance with site-directed mutagenesis, Larry Harris-Hailer for synthesis of oligonucleotides, and Valerian Dolja, Maria Restrepo-Hartwig, Xiao Hua Li, Deon Freed, and Kerri Braden for valuable comments on the manuscript. This work was supported in part by grants from the U.S. Department of Agriculture (89-37263-4503), the National Institute of Allergy and Infectious Disease (Al27842), and the Texas Advanced Technology Program.
PY - 1991/12
Y1 - 1991/12
N2 - The polyprotein encoded by plant potyviruses is proteolytically processed to at least eight mature products by viral-encoded proteinases. While the proteinases that catalyze processing at most of the cleavage sites have been identified, the enzyme responsible for cleavage between the 35-kDa protein and helper component-proteinase (HC-Pro), near the N-terminus of the viral polyprotein, has not been mapped or characterized previously. Polyproteins containing the 35-kDa protein and HC-Pro were synthesized in the wheat germ system using defined RNA transcripts and were demonstrated to undergo proteolysis to generate products that resemble fully processed proteins. The C-terminal half of the 35-kDa protein was found to be required for proteolysis, whereas most of the HC-Pro sequence was dispensable. Amino acid substitutions affecting three positions, each of which are conserved in the 35-kDa protein encoded by five potyviruses, were shown to inhibit protein processing. These data suggest that the 35-kDa protein functions as a proteinase to cleave at its C-terminus. A model that accounts for all proteolytic processing events in the potyviral polyprotein is presented.
AB - The polyprotein encoded by plant potyviruses is proteolytically processed to at least eight mature products by viral-encoded proteinases. While the proteinases that catalyze processing at most of the cleavage sites have been identified, the enzyme responsible for cleavage between the 35-kDa protein and helper component-proteinase (HC-Pro), near the N-terminus of the viral polyprotein, has not been mapped or characterized previously. Polyproteins containing the 35-kDa protein and HC-Pro were synthesized in the wheat germ system using defined RNA transcripts and were demonstrated to undergo proteolysis to generate products that resemble fully processed proteins. The C-terminal half of the 35-kDa protein was found to be required for proteolysis, whereas most of the HC-Pro sequence was dispensable. Amino acid substitutions affecting three positions, each of which are conserved in the 35-kDa protein encoded by five potyviruses, were shown to inhibit protein processing. These data suggest that the 35-kDa protein functions as a proteinase to cleave at its C-terminus. A model that accounts for all proteolytic processing events in the potyviral polyprotein is presented.
UR - http://www.scopus.com/inward/record.url?scp=0026349953&partnerID=8YFLogxK
U2 - 10.1016/0042-6822(91)90522-D
DO - 10.1016/0042-6822(91)90522-D
M3 - Article
C2 - 1962435
AN - SCOPUS:0026349953
SN - 0042-6822
VL - 185
SP - 527
EP - 535
JO - Virology
JF - Virology
IS - 2
ER -