FIG 4.

Late gene expression is persistent in σ^A* strains lacking ComW. Late gene expression patterns after CSP induction using a lacZ reporter at gene ssbB. β-Galactosidase activity (Miller units) in samples harvested every 10 min after CSP induction was measured in WT (σ^AWT), ΔcomW (σ^AWT), and σ^A* strains in the presence or absence of ComW. Each panel examines a different single amino acid substitution in σ^A, denoted as the WT amino acid, the position of the change, and the amino acid at that position: σ^A*^L363F (A), σ^A*^A171V (B), σ^A*^R316H (C), and σ^A*^R355H (D). Dashed lines, strains with WT σ^A; solid lines, strains with σ^A* suppressor mutations; red, strains with comW deletions; blue, strains with WT comW. Late gene expression was not detected without CSP induction of σ^X activity. Error bars, standard deviations from experiments performed in triplicate.