FIG. 5.

Analysis of transcription of the cip-cel operon based on deletions of the promoter region. (A) Various transcriptional fusions corresponding to different subregions of the cipC promoter were constructed by fusing promoter fragments (thick lines) to the SacI site located 30 bases upstream from the catP Shine-Dalgarno site. The putative transcriptional start sites, S1 and S2, are indicated by bent arrows, the −35 and −10 regions are indicated by open boxes, inverted and direct repeats are indicated by arrows, and the CRE element is indicated by a filled box. (B) CAT activity measured during the mid-exponential growth phase of C. cellulolyticum harboring the constructs. Cells were collected from 100-ml cultures containing 2 g liter⁻¹ cellobiose (at optical densities at 600 nm between 0.35 and 0.5) or 5 g liter⁻¹ cellulose (at cellular protein concentrations between 0.12 and 0.25 g liter⁻¹). Values obtained in two independent experiments are shown.