FIG. 2.

Yeast two-hybrid analysis of VirA^peri interactions. Saccharomyces cerevisiae EGY48 containing the plasmid pSH18-34, a reporter plasmid that carries a Gal1-lexAop-lacZ gene cluster, with a wild-type periplasmic domain (pMJ13) and the prey plasmid pJG4-5 expressing the P21 protein, was used as a negative control for this assay. The positive control was EGY48 containing pJK202 with a wild-type periplasmic domain and pMJ0 expressing the wild-type periplasmic domain of VirA (WT Peri). The experimental subjects were EGY48 containing pJK202 with a wild-type periplasmic domain and prey plasmids expressing VirA^peri mutants as shown. Shown here are four independent streaks of each strain on leucine-free solid media containing the chromogenic substrate X-Gal (5-bromo-4-chloro-3-indolyl-d-galactopyranoside). Blue is indicative of a positive interaction. See the text for a discussion of the results. EE-QL, Glu-254,Glu-255→Gln-254,Leu-255 mutant.