FIG. 5.

Modifications of the CP affecting its interaction with P2 in the yeast two-hybrid system. Yeast strain HF7c was cotransformed with plasmids encoding P2 in fusion with the Gal4AD (pGAD-P2) and the CP or CP derivatives in fusion with the Gal4BD (pGBT-CP, pGBT-CPΔ1, and pGBT-CPΔ2) (A) or with plasmids encoding P2 in fusion with the Gal4BD (pGBT-P2) and the CP versions in fusion with Gal4AD (pGAD-CP, pGAD-CPΔ730–732, pGAD-CPΔ736–739, pGAD-CPΔ749–769, pGAD-CP[C772A;C774A;C777A], and pGAD-CPΔ799–803; pGAD-CPM1 to pGAD-CPM6) (B and C). The β-galactosidase (β-gal.) activity was estimated by filter assay. Open boxes represent CP or CP derivatives in the CP fusion proteins, and interrupted black and gray boxes represent Gal4BD and Gal4AD, respectively. The basic domain of CP is indicated by a shaded box, and the zinc finger motif is indicated by a black circle. (B) Small deletions and replacements by alanines are indicated by V and arrows, respectively. (C) Alanine substitutions introduced in Gal4AD-CP fusion protein are shown in bold. Numbers indicated above open boxes and amino acid sequences refer to positions in the P3 polyprotein.