Regulates expression of the glpD operon. In the presence of glycerol 3-phosphate (G3P) causes antitermination of transcription of glpD at the inverted repeat of the leader region to enhance its transcription. Binds and stabilizes glpD leader mRNA. May also regulate expression of the glpFK operon. By glycerol 3-phosphate. Repressed by glucose, glucose 6-phosphate and fructose 6-phosphate. Defective in glycerol 3-phosphate uptake. Noninducible for glpK and glpD. Is able to grow at concentrations of the antibiotic fosfomycin that is not tolerated by the wild-type.