FIG. 2.

Spo0A(A257V) represses transcription from the abrB promoter in vitro. Phosphorylated or unphosphorylated mutant and wild-type (WT) Spo0A proteins were incubated with the initiating nucleotides ATP, UTP, and GTP and a linear DNA fragment encoding both the P1 and P2 transcription initiation sites of the abrB promoter. CTP and heparin were added 3 minutes after the addition of RNAPσ^A to permit transcript elongation. The reactions were terminated after 5 minutes, and the transcripts were separated by electrophoresis through an 8% denaturing polyacrylamide gel. ³²P-labeled abrB transcripts were detected by exposure to a phosphor screen (A), and the level of transcripts produced from the abrB promoter was determined by PhosphorImager analysis (B). Filled circles, Spo0A∼P; filled triangles, Spo0A; open circles, Spo0A(A257V)∼P; open triangles, Spo0A(A257V). Representative PhosphorImages are shown. The error bars indicate standard deviations.