Hepatitis C virus non-structural protein NS3 interacts with LMP7, a component of the immunoproteasome, and affects its proteasome activity.
NS3, a non-structural protein of the HCV (hepatitis C virus), contains a protease and a helicase domain and plays essential roles in the processing of the viral polyprotein, viral RNA replication and translation. LMP7 (low-molecular-mass protein 7), a component of the immunoproteasome, was identified as an NS3-binding protein from yeast two-hybrid screens, and this interaction was confirmed by in vitro binding and co-immunoprecipitation analysis. The minimal domain of interaction was defined to be between the pro-sequence region of LMP7 (amino acids 1-40) and the protease domain of NS3. To elucidate the biological importance of this interaction, we studied the effect of this interaction on NS3 protease activity and on LMP7 immunoproteasome activity. Recombinant LMP7 did not have any effect on NS3 protease activity in vitro. The peptidase activities of LMP7 immunoproteasomes, however, were markedly reduced when tested in a stable cell line containing a HCV subgenomic replicon. The down-regulation of proteasome peptidase activities could interfere with the processing of viral antigens for presentation by MHC class I molecules, and may thus protect HCV from host immune surveillance mechanisms to allow persistent infection by the virus.
Khu
Yee-Ling
YL
Collaborative Anti-Viral Research Group, Institute of Molecular and Cell Biology, 61 Biopolis Drive (Proteos), Singapore 138673, Singapore.
Tan
Yee-Joo
YJ
Lim
Seng Gee
SG
Hong
Wanjin
W
Goh
Phuay-Yee
PY
D000818:Animals; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D015723:Gene Library; D006367:HeLa Cells / Q000201:enzymology; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D009097:Multienzyme Complexes / Q000276:immunology / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry* / Q000378:metabolism*; D061988:Proteasome Inhibitors; D025941:Protein Interaction Mapping / Q000379:methods; D013154:Spleen / Q000737:chemistry / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D017361:Viral Nonstructural Proteins / Q000276:immunology / Q000378:metabolism*; D015003:Yeasts / Q000235:genetics; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
D009097:Multienzyme Complexes; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; D061988:Proteasome Inhibitors; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C077436:LMP7 protein