Characterization of the hepatitis C virus-encoded serine proteinase: determination of proteinase-dependent polyprotein cleavage sites.
Processing of the hepatitis C virus (HCV) H strain polyprotein yields at least nine distinct cleavage products: NH2-C-E1-E2-NS2-NS3-NS4A-NS4B-NS5A-NS5B-CO OH. As described in this report, site-directed mutagenesis and transient expression analyses were used to study the role of a putative serine proteinase domain, located in the N-terminal one-third of the NS3 protein, in proteolytic processing of HCV polyproteins. All four cleavages which occur C terminal to the proteinase domain (3/4A, 4A/4B, 4B/5A, and 5A/5B) were abolished by substitution of alanine for either of two predicted residues (His-1083 and Ser-1165) in the proteinase catalytic triad. However, such substitutions have no observable effect on cleavages in the structural region or at the 2/3 site. Deletion analyses suggest that the structural and NS2 regions of the polyprotein are not required for the HCV NS3 proteinase activity. NS3 proteinase-dependent cleavage sites were localized by N-terminal sequence analysis of NS4A, NS4B, NS5A, and NS5B. Sequence comparison of the residues flanking these cleavage sites for all sequenced HCV strains reveals conserved residues which may play a role in determining HCV NS3 proteinase substrate specificity. These features include an acidic residue (Asp or Glu) at the P6 position, a Cys or Thr residue at the P1 position, and a Ser or Ala residue at the P1' position.
Grakoui
A
A
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110-1093.
McCourt
D W
DW
Wychowski
C
C
Feinstone
S M
SM
Rice
C M
CM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D016174:Hepacivirus / Q000201:enzymology / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D020365:RNA Helicases; D011994:Recombinant Proteins / Q000378:metabolism; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases; D014616:Vaccinia virus / Q000235:genetics; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
D011498:Protein Precursors; D020365:RNA Helicases; D011994:Recombinant Proteins; D012697:Serine Endopeptidases; D017361:Viral Nonstructural Proteins; C080102:NS2B protein, flavivirus; C060028:NS3 protein, flavivirus; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases