Characterization of a multipurpose NS3 surface patch coordinating HCV replicase assembly and virion morphogenesis

Abstract

The hepatitis C virus (HCV) life cycle is highly regulated and characterized by a step-wise succession of interactions between viral and host cell proteins resulting in the assembly of macromolecular complexes, which catalyse genome replication and/or virus production. Non-structural (NS) protein 3, comprising a protease and a helicase domain, is involved in orchestrating these processes by undergoing protein interactions in a temporal fashion. Recently, we identified a multifunctional NS3 protease surface patch promoting pivotal protein-protein interactions required for early steps of the HCV life cycle, including NS3-mediated NS2 protease activation and interactions required for replicase assembly. In this work, we extend this knowledge by identifying further NS3 surface determinants important for NS5A hyperphosphorylation, replicase assembly or virion morphogenesis, which map to protease and helicase domain and form a contiguous NS3 surface area. Functional interrogation led to the identification of phylogenetically conserved amino acid positions exerting a critical function in virion production without affecting RNA replication. These findings illustrate that NS3 uses a multipurpose protein surface to orchestrate the step-wise assembly of functionally distinct multiprotein complexes. Taken together, our data provide a basis to dissect the temporal formation of viral multiprotein complexes required for the individual steps of the HCV life cycle.

Harnessing Nature’s Gifts: Salix nigra and Its Potential for Combating Hepatitis C Virus (HCV)

“…The unfolding of secondary structures within the HCV genome, the unwinding of the duplex generated by the positive and negative strands during replication, and the displacement of proteins that might prevent viral replication are some of the proposed functions of NS3 helicase. 9 NS3 protein is included in the DExH helicase family, which falls under superfamily 2. It moves in the 3′ to 5′ direction to exert unwinding action on RNA or DNA substrates.…”

“…It moves in the 3′ to 5′ direction to exert unwinding action on RNA or DNA substrates. 9 Medicinal plants are an important source of phytochemicals that are inclusively used in drug industries as raw materials. 10 Natural products are preferably used as synthetic drugs, which are associated with many side effects, whereas the former has low or no side effects.…”

“…NS3 protein is included in the DExH helicase family, which falls under superfamily 2. It moves in the 3′ to 5′ direction to exert unwinding action on RNA or DNA substrates …”

Design of Hepatitis C Protease Inhibitors Based on Knottin Fold

“…[2] HCV NS3 is a trifunctional protein that plays a crucial role in viral polyprotein processing and RNA replication. [3] NS3 Nterminal domain composed of 180 amino acids represents a serine protease, responsible for the proteolytic cleavage of the viral polyprotein. [4] The C-terminal part of the NS3 protein has helicase and NTPase activities.…”