OSMOTIC SHOCK INDUCTION OF CAPSULE SYNTHESIS IN ESCHERICHIA-COLI K-12

The genes (cps) involved in the synthesis of the colanic acid capsular polysaccharide in Escherichia coli K-12 are transcriptionally regulat ed by numerous proteins. Two of these, RcsB and RcsC, share homology w ith two-component regulatory elements that respond to environmental st imuli. Osmotic shock by sucrose or NaCl transiently increased transcri ption of a cpsB::lacZ fusion. RcsC and RcsB were essential for osmotic induction of colanic acid synthesis. In contrast to observations in s ome other osmotically regulated systems, addition of glycine betaine e nhanced the osmotic induction of cps::lacZ by both sucrose and NaCl bu t had no effect alone.