TABLE 2.

Effects of ssa mutations on Hap1 activity^a

Strain	β-Galactosidase activity (Miller units) when grown in the presence of the indicated concentration of dpIX
	0 μg/ml	0.05 μg/ml	0.25 μg/ml	1.0 μg/ml	4.0 μg/ml
Wild type	0.2 ± 0.1	72 ± 4	368 ± 55	360 ± 9	575 ± 69
a2a3a4	2.6 ± 0.4	85 ± 10	636 ± 88	649 ± 99	1,087 ± 35

^aYeast wild-type and a2a3a4 (with the SSA2, SSA3, and SSA4 genes deleted) cells bearing the Hap1-driven UAS1/CYC1-lacZ reporter were grown in the presence of 0, 0.05, 0.25, 1, and 4 μg of the heme analogue dpIX per ml. The HEM1 gene, encoding ALA synthase, was deleted from these strains to allow the experimental control of heme concentrations. β-Galactosidase activities were detected, and data shown are averages (± standard deviations) of at least three independent transformants.