TABLE 2.

Dominance and epistasis relationships among uhp regulatory gene alleles

uhp genotype of integrated plasmidb			β-Galactosidase activity from uhpT-lacZ reportera
			RK1294 (ΔuhpABC)		RK1300 (uhp+)
uhpA	uhpB	uhpC	−	+	−	+
+	+	+	2.5	660	3.5	450
+	+	91:4	2,610	2,070	970	960
+	+	91:8	6	6	2	170
15:4c	+	+	1.5	1	2	265
15:4c	+	91:4	1.5	1	835	710
15:4c	+	91:8	1.5	1	25	240
+	151:4	+	2,250	1,700	530	570
+	151:4	91:4	1,490	1,115	975	890
+	151:4	91:8	1,900	1,690	970	960
+	250:4d	+	750	1,060	610	800
+	250:4d	91:4	1,630	1,240	1,470	1,580
+	250:4d	91:8	25	25	215	375
+	87:4e	+	20	15	5	445
+	87:4e	91:4	40	30	470	565
+	87:4e	91:8	60	55	40	285

^aβ-Galactosidase activity was measured in the indicated uhp⁺ polA or ΔuhpABC polA strains into which the indicated plasmids bearing PstI linker insertions in uhp genes were introduced by transformation. Stable integrants, probably resulting from homologous recombination into the uhp locus, were selected by ampicillin resistance. Cells were grown in the absence (−) or presence (+) of Glu6P, as indicated, and β-galactosidase activity was measured as an average from three independent transformants, with variation of <10%. 

^bPlasmids are derivatives of pMI29 carrying PstI linker insertions (10). The location of the insertion is denoted by the amino acid residue preceding the site of insertion and the number of amino acids inserted. +, wild type. 

^cSimilar results were obtained with the uhpA169:4 and uhpA189:4 alleles. 

^dSimilar regulatory behavior was seen with the uhpB60:4 and uhpB387:4 alleles, which confer basal levels that are lower than those with uhpB250:4 but higher than with the wild type. 

^eSimilar results were obtained with the uhpB411:4 allele.