RNA Folding

Watching SAM flip the switch

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Science  03 Nov 2017:
Vol. 358, Issue 6363, pp. 605-606
DOI: 10.1126/science.358.6363.605-e

Riboswitches change their structure upon binding to a ligand, thereby altering downstream gene expression. Manz et al. report a map of the free-energy landscape of the S-adenosylmethionine (SAM)–binding SAM-I riboswitch derived from observing conformations of single molecules over many seconds. Changes in the free-energy landscape upon SAM binding shift the equilibrium toward the off state of the riboswitch, halting transcription. SAM binding also accelerates switching between on and off states, thus releasing switches kinetically trapped during transcription.

Nat. Chem. Biol. 10.1038/nchembio.2476 (2017).

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