Figure 3.

Effects of mutations in the α-σ⁷⁰ chimera or the additional −35 element on activation by λcI superactivator. (A) Schematic of test promoters used to determine the effect of mutating the additional −35 element on transcriptional activation by Sa109 in the presence of the α-σ⁷⁰ chimera. The sequences of the additional −35 elements from the two test promoters are indicated (consensus = TTGACA). (B) SF1 and SF2 cells harboring the indicated plasmids were assayed for β-galactosidase activity. In each panel, the sequence of the additional −35 element from the relevant test promoter is given. pACYC-derived plasmids encoded either λcISa109 [pACλcI(Sa109)] or λcISa109-Y38N [pACλcI(Sa109-Y38N)]; pBR322-derived plasmids encoded the α-σ⁷⁰ chimera (pBRα-σ⁷⁰), the α-σ⁷⁰ (R588H) chimera [pBRα-σ⁷⁰ (R588H)], or wild-type α (pBRα).