RNA Folding

Lighting up riboswitching

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Science  19 Jan 2018:
Vol. 359, Issue 6373, pp. 286-287
DOI: 10.1126/science.359.6373.286-e

RNAs fold as they are synthesized, and this folding is required for function. Uhm et al. describe a single-molecule fluorescence energy transfer assay to monitor cotranscriptional RNA folding. This approach revealed folding in the thiamine pyrophosphate (TPP) riboswitch that regulates translation of genes involved in the synthesis of thiamine, an essential vitamin. The riboswitch folds into the “off” conformation, in which translation is inhibited, even in the absence of the TPP ligand. If TPP is not bound to this off conformation, it can switch to the “on” conformation when transcription pauses near the translation start codon, and this allows translation to start. TPP binding stabilizes the off conformation and prevents the switch. The assay will allow investigation of other cases in which transcriptional speed and pausing affect RNA folding.

Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1712983115 (2017).

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