A single mutation in the core domain of the lac repressor reduces leakiness

Table 1 Amino acids at position 220 in naturally occurring repressors and those identified from screening the LacI W220X library

Naturally occurring				Identified after saturation mutagenesis
W	LacI			W
F	EbgR	CytR	PurR	F
S	MalI			S
L	TreR			L
P	GalR	GalS		V
Y	FruR	ExuR		I
T	AraR			M
				C

Amino acids found in other repressors of the GalR/LacI family are listed in the left column. Amino acids that allow LacI to retain the ability to bind to its operator DNA, and thus repress expression, are listed in the right column (in bold or italics to indicate whether they confer the I⁺ or I^s phenotype, respectively).

ISSN: 1475-2859