The acidic sequence of the NS4A cofactor regulates ATP hydrolysis by the HCV NS3 helicase.
In flaviviruses and hepatitis C virus (HCV), the NS3 gene encodes the N-terminal protease (NS3pro) and the C-terminal helicase (NS3hel). In HCV, the downstream NS4A is required for the NS3pro activity and exhibits a conserved EFDEMEE motif. To identify the role of this motif, we compared the ATPase and helicase activities of NS3 alone with those of the NS3-NS4A constructs. Our results suggest that the EFDEMEE motif is essential for regulating the ATPase activity of NS3hel. It is likely that this motif interferes with the ATP-binding site of NS3hel. It is becoming clear that NS4A functions as a cofactor of both proteinase and helicase in HCV.
Inflammatory and Infectious Disease Center, Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
Sergey A
SA
Shiryaev
Andrei V
AV
Chernov
Tatiana N
TN
Shiryaeva
Alexander E
AE
Aleshin
Alex Y
AY
Strongin
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D005814:Genes, Viral; D016174:Hepacivirus / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D047908:Intracellular Signaling Peptides and Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D020365:RNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
D000251:Adenosine Triphosphatases; D000255:Adenosine Triphosphate; D002352:Carrier Proteins; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D020365:RNA Helicases; D011993:Recombinant Fusion Proteins; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C455041:NS4A cofactor peptide, Hepatitis C virus