Mechanistic Role of an NS4A Peptide Cofactor with the Truncated NS3 Protease of Hepatitis C Virus:  Elucidation of the NS4A Stimulatory EffectviaKinetic Analysis and Inhibitor Mapping

Biochemistry ◽  
1997 ◽  
Vol 36 (31) ◽  
pp. 9340-9348 ◽  
Author(s):  
James A. Landro ◽  
Scott A. Raybuck ◽  
Yu Ping C. Luong ◽  
Ethan T. O'Malley ◽  
Scott L. Harbeson ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Ns3 Protease

scholarly journals Sequential Phosphorylation of the Hepatitis C Virus NS5A Protein Depends on NS3-Mediated Autocleavage between NS3 and NS4A

2020 ◽  
Vol 94 (19) ◽  
Author(s):  
Cho-Han Chiang ◽  
Yen-Ling Lai ◽  
Yu-Ning Huang ◽  
Chun-Chiao Yu ◽  
Christine C. Lu ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Nonstructural Protein ◽  
Necessary Condition ◽  
Cleavage Sites ◽  
Dual Functional ◽  
Genotype 2 ◽  
Hcv Protease ◽  
Ns3 Protease

ABSTRACT Replication of the genotype 2 hepatitis C virus (HCV) requires hyperphosphorylation of the nonstructural protein NS5A. It has been known that NS5A hyperphosphorylation results from the phosphorylation of a cluster of highly conserved serine residues (S2201, S2208, S2211, and S2214) in a sequential manner. It has also been known that NS5A hyperphosphorylation requires an NS3 protease encoded on one single NS3-5A polyprotein. It was unknown whether NS3 protease participates in this sequential phosphorylation process. Using an inventory of antibodies specific to S2201, S2208, S2211, and S2214 phosphorylation, we found that protease-dead S1169A mutation abrogated NS5A hyperphosphorylation and phosphorylation at all serine residues measured, consistent with the role of NS3 in NS5A sequential phosphorylation. These effects were not rescued by a wild-type NS3 protease provided in trans by another molecule. Mutations (T1661R, T1661Y, or T1661D) that prohibited proper cleavage at the NS3-4A junction also abolished NS5A hyperphosphorylation and phosphorylation at all serine residues, whereas mutations at the other cleavage sites, NS4A-4B (C1715S) or NS4B-5A (C1976F), did not. In fact, any combinatory mutations that prohibited NS3-4A cleavage (T1661Y/C1715S or T1661Y/C1976F) abrogated NS5A hyperphosphorylation and phosphorylation at all serine residues. In the C1715S/C1976F double mutant, which resulted in an NS4A-NS4B-NS5A fusion polyprotein, a hyperphosphorylated band was observed and was phosphorylated at all serine residues. We conclude that NS3-mediated autocleavage at the NS3-4A junction is critical to NS5A hyperphosphorylation at S2201, S2208, S2211, and S2214 and that NS5A hyperphosphorylation could occur in an NS4A-NS4B-NS5A polyprotein. IMPORTANCE For ca. 20 years, the HCV protease NS3 has been implicated in NS5A hyperphosphorylation. We now show that it is the NS3-mediated cis cleavage at the NS3-4A junction that permits NS5A phosphorylation at serines 2201, 2208, 2211, and 2214, leading to hyperphosphorylation, which is a necessary condition for genotype 2 HCV replication. We further show that NS5A may already be phosphorylated at these serine residues right after NS3-4A cleavage and before NS5A is released from the NS4A-5A polyprotein. Our data suggest that the dual-functional NS3, a protease and an ATP-binding RNA helicase, could have a direct or indirect role in NS5A hyperphosphorylation.

scholarly journals The possible role of NS3 protease activity of hepatitis C virus on fibrogenesis and miR-122 expression in hepatic stellate cells

2016 ◽  
Vol 60 (03) ◽  
pp. 242-248 ◽  
Author(s):  
S. KHANIZADEH ◽  
M. RAVANSHAD ◽  
S. Y. HOSSEINI ◽  
P. DAVOODIAN ◽  
A. N. ZADEH ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Hepatic Stellate Cells ◽  
Protease Activity ◽  
Stellate Cells ◽  
Ns3 Protease

Role of Charged Residues in the Catalytic Mechanism of Hepatitis C Virus NS3 Protease:  Electrostatic Precollision Guidance and Transition-State Stabilization

Biochemistry ◽  
2001 ◽  
Vol 40 (3) ◽  
pp. 631-640 ◽  
Author(s):  
Uwe Koch ◽  
Gabriella Biasiol ◽  
Mirko Brunetti ◽  
Daniela Fattori ◽  
Michele Pallaoro ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Transition State ◽  
Catalytic Mechanism ◽  
Transition State Stabilization ◽  
Charged Residues ◽  
Ns3 Protease

Role of autophagy in hepatitis C virus replication

2019 ◽  
Author(s):  
WI Twu ◽  
K Tabata ◽  
D Paul ◽  
R Bartenschlager
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Virus Replication
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