A comparative analysis of the substrate permissiveness of HCV and GBV-B NS3/4A proteases reveals genetic evidence for an interaction with NS4B protein during genome replication

作者：Benureau Yann; Warter Lucile; Malcolm Bruce A; Martin Annette^*

来源：Virology, 2010, 406(2): 228-240.

DOI：10.1016/j.virol.2010.07.014

• Hepacivirus
• Hepatitis C virus
• GB virus B
• Protease
• Substrate specificity
• Replication
• Mutagenesis
• Structural model
• NS3
• NS4B

The hepatitis C virus (HCV) serine protease (NS3/4A) processes the NS3-NS5B segment of the viral polyprotein and also cleaves host proteins involved in interferon signaling, making it an important target for antiviral drug discovery and suggesting a wide breadth of substrate specificity. We compared substrate specificities of the HCV protease with that of the GB virus B (GBV-B), a distantly related nonhuman primate hepacivirus, by exchanging amino acid sequences at the NS4B/5A and/or NS5A/5B cleavage junctions between these viruses within the backbone of subgenomic replicons. This mutagenesis study demonstrated that the GBV-B protease had a broader substrate tolerance, a feature corroborated by structural homology modeling. However, despite efficient polyprotein processing, GBV-B RNAs containing HCV sequences at the C-terminus of NS4B had a pseudo-lethal replication phenotype. Replication-competent revertants contained second-site substitutions within the NS3 protease or NS4B N-terminus, providing genetic evidence for an essential interaction between NS3 and NS4B during genome replication.

• 出版日期2010-10-25