Cross-genotypic interaction between hepatitis C virus NS3 protease domains and NS4A cofactors

• Published in: Journal of hepatology Vol. 32; no. 3; pp. 497 - 504
• Main Authors: WRIGHT-MINOGUE, J, NANHUA YAO, RUMIN ZHANG, BUTKIEWICZ, N. J, BAROUDY, B. M, LAU, J. Y. N, ZHI HONG
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 01.03.2000
• Subjects: Biological and medical sciences; Evolution, Molecular; Flaviviridae - metabolism; Genotype; Hepacivirus - genetics; Hepacivirus - metabolism; Human viral diseases; Infectious diseases; Medical sciences; Peptide Fragments - chemical synthesis; Peptide Fragments - pharmacology; RNA Helicases; Serine Endopeptidases; Viral diseases; Viral hepatitis; Viral Nonstructural Proteins - chemistry; Viral Nonstructural Proteins - genetics; Viral Nonstructural Proteins - physiology; Human; Immunopathology; Enzyme; Interaction; Genotype; Experimental study; Cofactor; In vitro; Protein; Infection; Virus; Peptidases; Characteristics; Viral disease; Genetics; Hydrolases; Cleavage; Flaviviridae; Hepatitis C virus; Hepacivirus
• ISSN: 0168-8278; 1600-0641
• DOI: 10.1016/s0168-8278(00)80402-x

Hepatitis C virus (HCV) nonstructural protein 3 (NS3) protease requires NS4A as a cofactor. This cofactor activity has been mapped to the central region of NS4A which interacts with the N-terminus of NS3 protease. To investigate whether this interaction is conserved among different genotypes of HCV cross-genotypic characterization were performed to delineate the importance of NS4A cofactor function in relation to the molecular evolution of HCV METHODS: Active NS3 protease domains of genotype 1-3 (representing five subtypes: la, 1b, 2a, 2b and 3a) were produced and purified from bacterial cells. NS4A cofactor-dependent in vitro trans cleavage assays were established using the in vitro translated recombinant protein substrates. These substrates contained the junction site of NS4A/NS4B, NS4B/NS5A or NS5A/NS5B. Our data revealed that NS3 proteases cross-interacted with NS4A cofactors derived from different genotypes, although the genotype 2 cofactor was less efficient, which could be due to greater genetic variations in this region. Furthermore, the corresponding region in hepatitis G virus (HGV) NS4A was found to provide weak cofactor activity for HCV NS3 protease. Surprisingly, a synthetic substrate peptide from the NS4B/NS5A junction was also found to enhance HCV NS3 protease activity in a dose-dependent manner. Our study suggests that the NS4A cofactor function is well conserved among HCV It is likely that other HCV-related viruses may have developed similar strategies to regulate their protease activity.