FIG 2.

Activating ligand specificity and necessity for SouR in sarcosine-dependent induction of the sox operon. (A) Results from a β-galactosidase assay of a ΔgbdR soxB′-lacZYA-′soxG strain exposed in MOPS-pyruvate (Pyr) to 1 mM either glycine betaine (GB), dimethylglycine (DM), sarcosine (Sarc), ethylglycine (EG), or glycine (Gly) or no compound (Pyr) as a control. For convenience, the structures for sarcosine and ethylglycine are shown over their respective bars. (B) Results of a β-galactosidase assay of a ΔgbdR ΔsouR soxB′-lacZYA-′soxG strain exposed in MOPS-pyruvate (Pyr) with or without 1 mM sarcosine with the addition of the empty vector (pMQ80) or the plasmid carrying souR and its native promoter (pSouR). Statistical significance was determined using one-way analysis of variance (ANOVA) with Dunnett's posttest, with the uninduced (Pyr) condition as the comparator for all other data. n.s., not significant; ***, P < 0.001; ****, P < 0.0001. The data shown are representative of the results of three independent experiments, and the error bars represent standard deviations.