TABLE 3.

Multiple mutations in the RhaS and RhaR linker regions

RhaS or RhaR derivative	β-Galactosidase activitya
	−l-Rhamnose	+l-Rhamnose
RhaS derivatives
Wild type	0.32	179
N168P/S169P	0.47	55
E167G/S169G/S171G	0.24	206
E167A/S169A/S171A	0.08	120
RhaS with RhaR linker	0.31	25
RhaR derivatives
Wild type	3.3	16
RhaR with RhaS linker	1	8.4

^aβ-Galactosidase activities are expressed in Miller units (19), with standard errors of less than 18% for RhaS derivatives and less than 14% for RhaR derivatives. The LacZ fusion did not contain the CRP binding sites, resulting in lower values than those in Tables 1 and 2.