Magnesium controls aptamer-expression platform switching in the SAM-I riboswitch

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dc.citation.firstpage3158
dc.citation.issueNumber6
dc.citation.journalTitleNucleic Acids Research
dc.citation.lastpage3170
dc.citation.volumeNumber47
dc.contributor.authorRoy, Susmita
dc.contributor.authorHennelly, Scott P.
dc.contributor.authorLammert, Heiko
dc.contributor.authorOnuchic, José Nelson
dc.contributor.authorSanbonmatsu, Karissa Y.
dc.date.accessioned2019-12-11T15:44:15Z
dc.date.available2019-12-11T15:44:15Z
dc.date.issued2019
dc.description.abstractInvestigations of most riboswitches remain confined to the ligand-binding aptamer domain. However, during the riboswitch mediated transcription regulation process, the aptamer domain and the expression platform compete for a shared strand. If the expression platform dominates, an anti-terminator helix is formed, and the transcription process is active (ON state). When the aptamer dominates, transcription is terminated (OFF state). Here, we use an expression platform switching experimental assay and structure-based electrostatic simulations to investigate this ON-OFF transition of the full length SAM-I riboswitch and its magnesium concentration dependence. Interestingly, we find the ratio of the OFF population to the ON population to vary non-monotonically as magnesium concentration increases. Upon addition of magnesium, the aptamer domain pre-organizes, populating the OFF state, but only up to an intermediate magnesium concentration level. Higher magnesium concentration preferentially stabilizes the anti-terminator helix, populating the ON state, relatively destabilizing the OFF state. Magnesium mediated aptamer-expression platform domain closure explains this relative destabilization of the OFF state at higher magnesium concentration. Our study reveals the functional potential of magnesium in controlling transcription of its downstream genes and underscores the importance of a narrow concentration regime near the physiological magnesium concentration ranges, striking a balance between the OFF and ON states in bacterial gene regulation.
dc.identifier.citationRoy, Susmita, Hennelly, Scott P., Lammert, Heiko, et al.. "Magnesium controls aptamer-expression platform switching in the SAM-I riboswitch." <i>Nucleic Acids Research,</i> 47, no. 6 (2019) Oxford University Press: 3158-3170. https://doi.org/10.1093/nar/gky1311.
dc.identifier.digitalgky1311
dc.identifier.doihttps://doi.org/10.1093/nar/gky1311
dc.identifier.urihttps://hdl.handle.net/1911/107842
dc.language.isoeng
dc.publisherOxford University Press
dc.rightsThis work is written by (a) US Government employee(s) and is in the public domain in the US.
dc.titleMagnesium controls aptamer-expression platform switching in the SAM-I riboswitch
dc.typeJournal article
dc.type.dcmiText
dc.type.publicationpublisher version
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