TABLE 2

Structure-based design of the CSFV NS3 protease-helicase interface mutations

NameaMutation(s)Deleted residuesDescriptions/notes
WTNAbNA
Set 1C-terminal tail (interacting with protease active site)
    TAIL_Δ2NA680–681Keep P1 (G682) and P2 (L683) residues
    TAIL_Δ4NA675–678Remove one helix turn, keep the β-type region 680–683
Set 2Salt bridges and hydrophobic cap
    CEX_1R551E, E571RNACharge exchange within helicase
    CEX_2E141K, K183ENACharge exchange within protease
    CAP_1Y555FNAKeep hydrophobic interactions with G139/G140
    CAP_2Y555ANAReduce hydrophobic interactions with G139/G140
Set 3Hydrogen bonding and hydrophobic network
    HB_1N93ANADisrupt a hydrogen bond
    HB_2N93DNAInterfere with the hydrogen bonding network
    HB_3S525ANADisrupt a hydrogen bond
    HB_4E561DNAShorten the side chain but preserve the charge
  • a The WT enzyme contains the NS4APCS (residues 21 to 57) and the full-length NS3 as the N- and C-terminal regions, respectively. The S163A mutation was introduced to abolish the autocleavage activity of the protease in all protein constructs listed here. Mutation sets 1, 2, and 3 are according to interface interaction clusters 1, 2, and 3.

  • b NA, nonapplicable.