Activates the small RNA gene sgrS under glucose-phosphate stress conditions as well as yfdZ. Represses its own transcription under both stress and non-stress conditions; this repression likely provides one measure of control over sgrR at the level of synthesis. Might act as a sensor of the intracellular accumulation of phosphoglucose by binding these molecules in its C-terminal solute-binding domain. Binds specifically to sgrS promoter in vitro.