FIG 11.

Structural comparison of NS5A and UL44. Shown are side (A) and top (B) views of HCV NS5A (PDB code 1ZH1) and side (C) and top (D) views of CMV UL44 (PDB code 1T6L) processivity factor, as well as side (E) and top (F) views of the structural overlays of NS5A and UL44. The similarity of dimeric forms of HCV NS5A and CMV UL44 is interesting. The lining of basic residues in the cavity is observed for the two structures. However, the cavity is larger for UL44 than NS5A. The broader similarities may be used to infer a processivity role for NS5A. However, the C clamps are very different from each other. There is no similarity between the structural elements of the two proteins. Head-to-head interfaces for the two proteins are assembled quite differently.