Post-translational modification of the hepatitis C virus core protein by tissue transglutaminase.
The hepatitis C virus (HCV) core protein is a structural protein that packages the viral genomic RNA. In this study, we demonstrate that a stable core protein dimer could be produced in liver cells. The production of this protein could be enhanced by calphostin C and serum deprivation. This protein was determined to be the core protein dimer because of its reactivity with the anti-core antibody, its similar electrophoretic mobility compared with that of the core protein dimer generated by cross-linking with glutaraldehyde, and its increase in size by a hemagglutinin tag fused to the core protein sequence. This core protein dimer was highly stable and resistant to SDS and beta-mercaptoethanol. The enzyme that mediated the formation of this stable core protein dimer was determined to be the tissue transglutaminase (tTG) because, first, tTG could be activated by calphostin C and serum deprivation; second, the formation of this dimer was suppressed by monodansylcadaverine, a tTG inhibitor; and third, the core protein could be cross-linked by tTG in vitro. Thus, the HCV core protein represents the first known viral structural protein substrate of tTG. The post-translational modification by tTG reduced the RNA binding activity of the core protein, raising the possibility that tTG may regulate the biological functions of the HCV core protein.
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Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
Strohecker
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Ou Jh
J H
JH
D002460:Cell Line; D016895:Culture Media, Serum-Free; D019281:Dimerization; D004789:Enzyme Activation; D016174:Hepacivirus / Q000378:metabolism*; D009281:Naphthalenes / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D011503:Transglutaminases / Q000378:metabolism*; D014758:Viral Core Proteins / Q000378:metabolism*
D016895:Culture Media, Serum-Free; D009281:Naphthalenes; D014758:Viral Core Proteins; D011503:Transglutaminases; D011493:Protein Kinase C; C058819:calphostin C