TABLE 3.

β-Galactosidase expression from tyrP-lac fusions on plasmids pMU2055 and pMU6449^a

Plasmid	tyrP −35 region (sequence)	β-Galactosidase activity for:
		tyrR366	tyrR+
			MM	MM + Tyr	MM + Phe
pMU2055	Wild type (TTGACG)	130	138	850	1,560
pMU6449	Mutant (TTGCCG)	8	4	31	67

^aThe plasmids were present in strain JP8042 (tyrR366) or JP7740 (tyrR⁺). Methods for growth and enzyme assays were as described in the footnote to Table 1, with the modification that the minimal salts medium (MM) used was prepared from half-strength medium 56. Tyr or Phe supplementation was at 1 mM. Enzyme specific activity values are reported in Miller units (24).