Transcriptional analysis of the Bacillus subtilis teichuronic acid operon

The cell walls of Gram-positive bacteria consist primarily of a macromolecular matrix comprising similar amounts of peptidoglycan and covalently attached anionic polymers. Under most growth conditions the anionic polymers of Bacillus subtilis are principally teichoic acids; in strain 168 these include a polyglycerol teichoic acid and a glucose/galactosamine-containing teichoic acid. However, when cultures are subjected to phosphate stress the bacterium induces a complex series of responses, one of which is the replacement of at least part of the wall teichoic acid with teichuronic acid, a non-phosphate-containing anionic polymer. In this paper the construction of a transcriptional reporter strain that facilitates the monitoring of the promoter region upstream of the tua operon involved in teichuronic acid synthesis and its controlled expression are reported. The expression of the tua operon was monitored in both phosphate-starved, non-growing batch cultures and phosphate-limited continuous cultures. We show that the transcription of the operon correlates well with the anionic polymer composition of the cell walls.