TY - JOUR
T1 - Characterization of the potyviral HC-pro autoproteolytic cleavage site
AU - Carrington, James C.
AU - Herndon, Kerri L.
N1 - Funding Information:
We thank Valerian Dolja, Deon Freed, Xiao Hua Li, Maria Res-trepo-Hartwig, and Jeanmarie Verchot for their helpful comments on this manuscript; Larry HarrisHaIler for synthesis of oligonucleotides; Vince Cassone for assistance with the video image analysis of autoradiographs; and members of the Friday Institute for their advice. This work was supported in part by a USDA Competitive Grant (9 l-37303.6435) and a Public Health Service Grant (Al27842) from the National Institute of Allergy and Infectious Disease.
PY - 1992/3
Y1 - 1992/3
N2 - The helper component-proteinase (HC-Pro) encoded by potyviruses functions to cleave the viral polyprotein by an autoproteolytic mechanism at the HC-Pro C-terminus. This protein belongs to a group of viral cysteine-type proteinases and has been shown previously to catalyze proteolysis between a Gly-Gly dipeptide. The amino acid sequence requirements surrounding the HC-Pro C-terminal cleavage site of the tobacco etch virus polyprotein have been investigated using site-directed mutagenesis and in vitro expression systems. A total of 51 polyprotein derivatives, each differing by the substitution of a single amino acid between the P5 and P2′ positions, were tested for autoproteolytic activity. Substitutions of Tyr (P4), Val (P2), Gly (P1), and Gly (P1′) were found to eliminate or nearly eliminate proteolysis. Substitutions of Thr (P5), Asn (P3), and Met (P2′), on the other hand, were permissive for proteolysis, although the apparent processing rates of some polyproteins containing these alterations were reduced. These results suggest that auto-recognition by HC-Pro involves the interaction of the enzymatic binding site with four amino acids surrounding the cleavage site. Comparison of the homologous sequences of five potyviral polyproteins revealed that the residues essential for processing are strictly conserved, whereas the nonessential residues are divergent. The relationship between HC-Pro and other viral and cellular cysteine-type proteinases is discussed.
AB - The helper component-proteinase (HC-Pro) encoded by potyviruses functions to cleave the viral polyprotein by an autoproteolytic mechanism at the HC-Pro C-terminus. This protein belongs to a group of viral cysteine-type proteinases and has been shown previously to catalyze proteolysis between a Gly-Gly dipeptide. The amino acid sequence requirements surrounding the HC-Pro C-terminal cleavage site of the tobacco etch virus polyprotein have been investigated using site-directed mutagenesis and in vitro expression systems. A total of 51 polyprotein derivatives, each differing by the substitution of a single amino acid between the P5 and P2′ positions, were tested for autoproteolytic activity. Substitutions of Tyr (P4), Val (P2), Gly (P1), and Gly (P1′) were found to eliminate or nearly eliminate proteolysis. Substitutions of Thr (P5), Asn (P3), and Met (P2′), on the other hand, were permissive for proteolysis, although the apparent processing rates of some polyproteins containing these alterations were reduced. These results suggest that auto-recognition by HC-Pro involves the interaction of the enzymatic binding site with four amino acids surrounding the cleavage site. Comparison of the homologous sequences of five potyviral polyproteins revealed that the residues essential for processing are strictly conserved, whereas the nonessential residues are divergent. The relationship between HC-Pro and other viral and cellular cysteine-type proteinases is discussed.
UR - https://www.scopus.com/pages/publications/0026582219
U2 - 10.1016/0042-6822(92)90319-K
DO - 10.1016/0042-6822(92)90319-K
M3 - Article
C2 - 1736533
AN - SCOPUS:0026582219
SN - 0042-6822
VL - 187
SP - 308
EP - 315
JO - Virology
JF - Virology
IS - 1
ER -