Dynamic competition between a ligand and transcription factor NusA governs riboswitch-mediated transcription regulation.

ABSTRACT: Cotranscriptional RNA folding is widely assumed to influence the timely control of gene expression, but our understanding remains limited. In bacteria, the fluoride (F^-)-sensing riboswitch is a transcriptional control element essential to defend against toxic F^- levels. Using this model riboswitch, we find that its ligand F^- and essential bacterial transcription factor NusA compete to bind the cotranscriptionally folding RNA, opposing each other's modulation of downstream pausing and termination by RNA polymerase. Single-molecule fluorescence assays probing active transcription elongation complexes discover that NusA unexpectedly binds highly reversibly, frequently interrogating the complex for emerging, cotranscriptionally folding RNA duplexes. NusA thus f

SUBMITTER: Chauvier A 

PROVIDER: S-EPMC8617461 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature