FIG. 3.

Analysis of amino acid determinants of VPg-PVIP interactions. (A) VPg sequences from TuMV, LMV, PSbMV, and TEV were aligned using the Clustal W program. Only regions 1 to 16 and 42 to 66 are shown. Identical (*) and related (:) amino acids for the four sequences are indicated. Amino acid positions where TEV differed from the other three with an unrelated residue are also identified (▴). (B) Mutational analysis of TuMV and TEV VPg proteins targeting aa 3, 12, or 14. The TuMV point mutants Tu G3-, F12M, and N14E and the TEV point mutant Te M12F (shaded) were tested for interaction with PVIP1 (column 1), PVIP2 (column 2), PVIPp (column p), and PVIPnb (column Nb) using yeast two-hybrid analysis. Interactions in yeast were scored qualitatively; all the positive (+) interactions were seen as equivalent yeast growth on selective media.