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. 2017 Jan 10;8:13892. doi: 10.1038/ncomms13892

Figure 1. The thiC riboswitch controls gene expression at the levels of transcription and translation.

Figure 1

(a) Secondary structure of the thiC riboswitch representing the TPP-bound state. The P1 stem, the RBS and the start codon are represented in green, blue and red, respectively. The anti-P1 stem is shown in orange rectangles. The nomenclature of the helical domains is based on a previous study12. (b) Schematic representing the TPP-free state determined in this study. The colour scheme is the same as in a. (c) β-Galactosidase assays of translational ThiC–lacZ (trL) and transcriptional thiC–lacZ (trX) fusions for the wild type, ON, OFF and G31C mutants. Values were normalized to the activity obtained for the wild type in the absence of TPP. The average values of three independent experiments with s.d.'s are shown. (d) β-Galactosidase assays of transcriptional thiC-lacZ (trX) performed in the context of the wild-type and rne-131 strains. Values were normalized to the activity obtained for the wild type in absence of TPP. The average values of three independent experiments with s.d.'s are shown. (e) β-Galactosidase assays of transcriptional thiC–lacZ (trX) performed in the wild type in absence or presence of TPP or bicyclomycin (BCM). Values were normalized to the activity obtained for the wild type in absence of TPP. The average values of three independent experiments with s.d.'s are shown. (f) In vitro Rho-dependent transcription performed using the thiC riboswitch. Full-length (FL) and termination (T) products are indicated on the left. Termination efficiencies are indicated below for reactions done with Rho. Termination products are indicated on the right. (g) Transcription–translation-coupled in vitro assays using the wild type and G31C mutant. Reactions were performed in absence (−) or presence (+) of TPP. Translation products are shown on the left and ratios of ThiC expression are normalized to that of LacZ. (h) Transcription–translation-coupled in vitro assays using the wild-type riboswitch. The half transition of translation repression corresponds to a value of 1.7±0.3 μM.