Table 2.

Mutations in SRB10, SRB11, andCTK1 affect repression of CYC1-lacZby LexA-Tup1a

ProteinGenotypeβ-Gal activitybFold repressionc
−LexAop+LexAop
5′ to UAS
 LexAWT162951.7
srb10Δ 2772071.3
srb11Δ 2702001.4
srb10-D290A 2811292.2
ctk1Δ 2471571.6
 LexA-Tup1WT1027.514
srb10Δ 1821051.7
srb11Δ 1521151.3
srb10-D290A 240872.8
ctk1Δ 60183.3
3′ to UAS
 LexAWT167364.6
srb10Δ 321943.4
 LexA-Tup1WT1242.159
srb10Δ 261426.2
  • a Isogenic wild-type (WT) and mutant strains were cotransformed with plasmid YCp91 or pLexA-Tup1 (58) expressing LexA and LexA-Tup1, respectively, andCYC1-lacZ reporter plasmids (Fig. 1) with no LexA operator (−LexAop) or one LexA operator (+LexAop) located 5′ or 3′ to UASCYC1, as indicated.

  • b β-Galactosidase (β-Gal) activity was assayed in protein extracts, and values are averages for 4 to 10 independent transformants. Standard errors were typically 10 to 15%.

  • c Fold repression was calculated as the ratio of the values obtained for reporters with and without a LexA operator. The host strains were FY250, MCY3655, MCY3661, MCY3662, MCY3664, and MCY3694.