FIG. 2.

Genetic analysis of the YsrS-YsrT-YsrR phosphorelay. Assays of β-galactosidase activity in strains harboring a ysaE-lacZ reporter were used to evaluate the role of each protein. Saturated cultures grown in L broth were subcultured into fresh L broth (noninducing) or LB-290 (inducing) and grown for 2 h at 26°C on a roller drum. Each protein is represented in cartoon form, with a different shape for each domain type. Solid, gene is single copy (chromosomal); hatched, gene is carried on a multicopy plasmid. Point mutations are indicated above the respective domains. The relevant genotype is given on the left, and the relative promoter activity is given on the right in Miller units with the standard deviation in parentheses. The strains and plasmids used to evaluate (A) YsrS, (B) YsrT, and (C) YsrR are listed in Table 1. WT, wild type.