FIG. 4.
Determination of the prtR transcription start point. (A) Primer extension analysis of the prtR promoter was performed with RNA from L. casei ATCC 393T cells harboring pEB471. (B) L. casei ATCC 393T cells harboring pEB640 (lane 1) and L. rhamnosus BGT10 (lane 2). The sequencing reactions (A, C, G, and T) were performed with the same primers as the corresponding primer extension reactions. The primer extension products are indicated with an arrow. (C) Interpretation of the primer extension results. The putative −35 and −10 prtR promoter haxamers (underlined), the transcription start point (+1, underlined), and the putative ribosome binding site (RBS) (boldface) are shown. The prtR coding sequence is in italic.