TABLE 2.

Effect of ppGpp on rpoS-lac and lac expression in vivo^a

lac fusion		Fusion type	β-Galactosidase activity (U)						Activity ratio, mutant/wild type
			Wild type			Mutant (ppGpp°)
Promoter	Reporter		E	S + 3	S + 3/E	E	S + 3	S + 3/E	E	S + 3	S + 3/E
rpoS	rpoS-lac	Protein	3.4	120	35	0.54	5.1	9.4	0.16	0.04	0.27
rpoS	rpoS-lac	Operon	35	510	15	11	50	4.5	0.31	0.10	0.31
lacUV5	rpoS-lac	Protein	5.3	71	13	2.1	7.6	3.6	0.40	0.11	0.27
lacUV5	rpoS-lac	Operon	100	330	3.3	64	130	2.0	0.64	0.39	0.61
lacUV5	rpoS-lac (+1)	Protein	10	130	13	3.2	25	7.8	0.32	0.19	0.60
rpoS	rpoS-lac (codon 8)b	Protein	4	130	32	0.62	13	21	0.15	0.10	0.64
lacUV5	lac	Operon	120	160	1.3	81	80	0.99	0.67	0.50	0.74

^aExponential-phase (E) and stationary-phase (S + 3) samples are defined in the text. Values are averages with a variation of <20%, with one exception noted in the text. The S + 3/E induction ratio was calculated as the activity of the S + 3 sample divided by that of the E sample.

^bAll other fusions were to codon 73 of rpoS.