TABLE 6.

Effects of alanine substitutions in CRP AR1 and AR2 at rhaS-lacZ fusions

CRP derivative	Φ(rhaS-lacZ)Δ216		Φ(rhaS-lacZ)Δ128
	β-Gal sp acta	% Wt sp act	β-Gal sp acta	% Wt sp act
Wt	200	100	676	100
T158A	325	163	557	82
G162A	181	90	290	43
H19A	244	122	437	65
H21A	178	89	221	33
K101A	215	108	579	86

^aβ-Galactosidase (β-Gal) specific activity was measured from a single-copy rhaS-lacZ fusion in a crp deletion strain transformed with plasmids encoding either a wild-type or mutant form of CRP. Cultures were grown in MOPS media containing glycerol, l-rhamnose, and ampicillin. Standard errors were less than 18% of the average units. Wt, wild type.