Hepatitis C virus NS5A protein interacts with 2',5'-oligoadenylate synthetase and inhibits antiviral activity of IFN in an IFN sensitivity-determining region-independent manner.
The non-structural protein 5A (NS5A) of hepatitis C virus (HCV) has been implicated in inhibition of antiviral activity of IFN. While previous studies have suggested an interaction between NS5A and the double-stranded RNA-dependent protein kinase (PKR), the possibility still remains that interaction with another molecule(s) is involved in the NS5A-mediated inhibition of IFN. In the present study, we investigated a possible interaction between NS5A and 2',5'-oligoadenylate synthetase (2-5AS), another key molecule in antiviral activity. We observed that NS5A physically interacted with 2-5AS in cultured cells, with an N-terminal portion of NS5A [aa 1-148; NS5A(1-148)] and two separate portions of 2-5AS (aa 52-104 and 184-275) being involved in the interaction. Single point mutations at residue 37 of NS5A affected the degree of the interaction with 2-5AS, with a Phe-to-Leu mutation (F37L) augmenting and a Phe-to-Asn mutation (F37N) diminishing it. Virus rescue assay revealed that the full-length NS5A (NS5A-F) and NS5A(1-148), the latter of which contains neither the IFN sensitivity-determining region (ISDR) nor the PKR-binding domain, significantly counteracted the antiviral activity of IFN. Introduction of a F37N mutation into NS5A(1-148) impaired the otherwise more significant IFN-inhibitory activity of NS5A(1-148). It was also found that the F37N mutation was highly disadvantageous for the replication of an HCV RNA replicon. Taken together, our results suggest the possibility that NS5A interacts with 2-5AS and inhibits the antiviral activity of IFN in an ISDR-independent manner.
Taguchi
Takashi
T
Division of Diabetes, Digestive and Kidney Diseases, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.|Division of Microbiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
Nagano-Fujii
Motoko
M
Division of Microbiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
Akutsu
Masato
M
Division of Microbiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
Kadoya
Hiroyasu
H
Division of Microbiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
Ohgimoto
Shinji
S
Division of Microbiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
Ishido
Satoshi
S
Division of Microbiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
Hotta
Hak
H
Division of Microbiology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
D015088:2',5'-Oligoadenylate Synthetase / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004279:DNA, Viral / Q000235:genetics; D006367:HeLa Cells; D016174:Hepacivirus / Q000235:genetics / Q000502:physiology*; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000037:antagonists & inhibitors*; D051379:Mice; D016297:Mutagenesis, Site-Directed; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins; D017384:Sequence Deletion; D014162:Transfection; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D012324:RNA-Dependent RNA Polymerase
D015088:2',5'-Oligoadenylate Synthetase; D004279:DNA, Viral; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase