title: Hepatitis C virus NS4A inhibits cap-dependent and the viral IRES-mediated translation through interacting with eukaryotic elongation factor 1A.
abstract: The genomic RNA of hepatitis C virus (HCV) encodes the viral polyprotein precursor that undergoes proteolytic cleavage into structural and nonstructural proteins by cellular and the viral NS3 and NS2-3 proteases. Nonstructural protein 4A (NS4A) is a cofactor of the NS3 serine protease and has been demonstrated to inhibit protein synthesis. In this study, GST pull-down assay was performed to examine potential cellular factors that interact with the NS4A protein and are involved in the pathogenesis of HCV. A trypsin digestion followed by LC-MS/MS analysis revealed that one of the GST-NS4A-interacting proteins to be eukaryotic elongation factor 1A (eEF1A). Both the N-terminal domain of NS4A from amino acid residues 1-20, and the central domain from residues 21-34 interacted with eEF1A, but the central domain was the key player involved in the NS4A-mediated translation inhibition. NS4A(21-34) diminished both cap-dependent and HCV IRES-mediated translation in a dose-dependent manner. The translation inhibitory effect of NS4A(21-34) was relieved by the addition of purified recombinant eEF1A in an in vitro translation system. Taken together, NS4A inhibits host and viral translation through interacting with eEF1A, implying a possible mechanism by which NS4A is involved in the pathogenesis and chronic infection of HCV.
authors.affiliation: Institute of Microbiology, National Taiwan University College of Medicine, No.1, Sec.1, Jen-Ai Road, Taipei, Taiwan, Republic of China.
authors.forename: Yi-Hen
authors.initials: YH
authors.lastname: Kou
authors.forename: Shang-Min
authors.initials: SM
authors.lastname: Chou
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Wang
authors.forename: Ya-Tzu
authors.initials: YT
authors.lastname: Chang
authors.forename: Shao-Yong
authors.initials: SY
authors.lastname: Huang
authors.forename: Mei-Ying
authors.initials: MY
authors.lastname: Jung
authors.forename: Yu-Hsu
authors.initials: YH
authors.lastname: Huang
authors.forename: Mei-Ru
authors.initials: MR
authors.lastname: Chen
authors.forename: Ming-Fu
authors.initials: MF
authors.lastname: Chang
authors.forename: Shin C
authors.initials: SC
authors.lastname: Chang
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1 / Q000378:metabolism*; D014176:Protein Biosynthesis; D012315:RNA Caps; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; C455041:NS4A cofactor peptide, Hepatitis C virus; D020648:Peptide Elongation Factor 1; D012315:RNA Caps; D012333:RNA, Messenger; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins