TABLE 2.

Effect of cAMP on repression of the glxR gene^a

Host cells	Plasmid	Relevant genotype	cAMP	Relative β-galactosidase activity
E. coli HL994	pMT1	cya+	−	1
	pSL329-5	cya+glxR	−	0.52 ± 0.06
E. coli HL989	pMT1	cya	−	1
	pSL329-5	cya glxR	−	0.91 ± 0.07
	pSL329-5	cya glxR	+	0.37 ± 0.05

^aCells were grown on LB medium, and cell extracts were prepared as described in Materials and Methods. P_aceB-lacZYA was introduced into the chromosome as described in Materials and Methods. cAMP was added to a final concentration of 10 mM.