FIG. 3.

Phosphorylation of Crr is crucial for rpoS regulation. (A) Complementation assay of the crr::kan mutant. Strains CU263 (wild type) and CU330 (crr::kan) carrying plasmid pTSV28 (vector [vec.]), pSTCRR (crr⁺), or pST172 (crrH90Q) were grown at 37°C in Luria broth supplemented with 25 μg of chloramphenicol per ml. At the mid-logarithmic phase, β-galactosidase activity (upper panel) and ς^S content (lower panel) were measured. (B) Effect of the ptsHI or ptsG mutation on rpoS expression. Strains CU344 (wild type [WT^*]), CU345 (ΔptsHI), CU263 (wild type), and CU348 (ptsG::Tn5) were grown at 37°C in Luria broth. Note that CU344 and CU345 carry the nupC510::Tn10 allele, which was used as a selectable marker to construct the ΔptsHI mutant. At the mid-logarithmic phase, β-galactosidase activity expressed by PF977 (upper panel) and ς^S content (lower panel) were measured. β-Galactosidase activity data are means with standard deviations for four independent assays. Each 20 μg of total proteins was used for immunoblotting.