Major determinant of cell surface composition. Negatively regulates motility, adhesion and synthesis of biofilm exopolysaccharides. Expression is dependent on RpoS. Deletion mutants show increased flagella and fimbriae production, are hypermotile, and exhibit increased biofilm formation. Belongs to the GlgS family. Was originally thought to be involved in glycogen synthesis, but it was shown later that its effect on glycogen metabolism is probably indirect.