ACETYL PHOSPHATE AND THE ACTIVATION OF 2-COMPONENT RESPONSE REGULATORS

Several bacterial response regulator proteins (CheY, NR(1), PhoB, and OmpR) become phosphorylated in vitro when incubated with acetyl phosph ate. In the presence of high levels of acetyl phosphate and Mg2+, CheY reached steady state phosphorylation in less than 30 s; NR(I) and Pho B reached steady state more slowly (t1/2 to steady state of 1.5 and >1 5 min, respectively). A simple method was developed to measure acetyl phosphate levels in Escherichia coli grown in defined media, Levels of acetyl phosphate were elevated in cells grown in pyruvate, glucose, a nd glucuronic acid and were low in cells grown in fructose, glycerol, and fumarate. The effects of varying the intracellular amounts of acet yl phosphate on chemotaxis and the osmo-response were also investigate d, Acetyl phosphate was not required but did influence each of these r esponses, These results suggest that acetyl phosphate may influence ei ther the sensitivity or the magnitude of an adaptive response.