Article

Interaction of hepatitis C virus nonstructural protein 5A with core protein is critical for the production of infectious virus particles.

Department of Virology II, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
Journal of Virology (impact factor: 5.4). 08/2008; 82(16):7964-76. DOI:10.1128/JVI.00826-08 pp.7964-76
Source: PubMed

ABSTRACT Nonstructural protein 5A (NS5A) of the hepatitis C virus (HCV) possesses multiple and diverse functions in RNA replication, interferon resistance, and viral pathogenesis. Recent studies suggest that NS5A is involved in the assembly and maturation of infectious viral particles; however, precisely how NS5A participates in virus production has not been fully elucidated. In the present study, we demonstrate that NS5A is a prerequisite for HCV particle production as a result of its interaction with the viral capsid protein (core protein). The efficiency of virus production correlated well with the levels of interaction between NS5A and the core protein. Alanine substitutions for the C-terminal serine cluster in domain III of NS5A (amino acids 2428, 2430, and 2433) impaired NS5A basal phosphorylation, leading to a marked decrease in NS5A-core interaction, disturbance of the subcellular localization of NS5A, and disruption of virion production. Replacing the same serine cluster with glutamic acid, which mimics the presence of phosphoserines, partially preserved the NS5A-core interaction and virion production, suggesting that phosphorylation of these serine residues is important for virion production. In addition, we found that the alanine substitutions in the serine cluster suppressed the association of the core protein with viral genome RNA, possibly resulting in the inhibition of nucleocapsid assembly. These results suggest that NS5A plays a key role in regulating the early phase of HCV particle formation by interacting with core protein and that its C-terminal serine cluster is a determinant of the NS5A-core interaction.

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Keywords

alanine substitutions
 
C-terminal serine cluster
 
core protein
 
diverse functions
 
domain III
 
HCV particle production
 
hepatitis C virus
 
infectious viral particles
 
Nonstructural protein 5A
 
NS5A basal phosphorylation
 
NS5A participates
 
NS5A-core interaction
 
nucleocapsid assembly
 
serine cluster
 
serine cluster suppressed
 
viral capsid protein
 
viral genome RNA
 
virion production
 
virus production
 
virus production correlated