Teichuronic acid operon of Bacillus subtilis 168

Sequence analysis reveals that the Bacillus subtilis 168 tuaABCDEFGHoperon encodes enzymes required for the polymerization of teichuronic acid as well as for the synthesis of one of its precursors, the UDP-glucuronate. Mutant s deficient in any of the tua genes, grown in batch cultures under conditio ns of phosphate limitation, were characterized by reduced amounts of uronat e in their cell walls. The teichuronic acid operon belongs to the Pho regul on, as phosphate limitation induces its transcription. Placing the tuaABCDE FGH operon under the control of the inducible P-spac promoter allowed its c onstitutive expression independently of the phosphate concentration in the medium; the level of uronic acid in cell walls was dependent on the concent ration of the inducer. Apparently, owing to an interdependence between teic hoic and teichuronic acid incorporation into the cell wall, in examined gro wth conditions, the balance between the two polymers is maintained in order to insure a constant level of the wall negative charge.