Precise tuning of bacterial translation initiation by non-equilibrium 5'-UTR unfolding observed in single mRNAs.

ABSTRACT: Noncoding, structured 5'-untranslated regions (5'-UTRs) of bacterial messenger RNAs (mRNAs) can control translation efficiency by forming structures that either recruit or repel the ribosome. Here we exploit a 5'-UTR embedded preQ1-sensing, pseudoknotted translational riboswitch to probe how binding of a small ligand controls recruitment of the bacterial ribosome to the partially overlapping Shine-Dalgarno (SD) sequence. Combining single-molecule fluorescence microscopy with mutational analyses, we find that the stability of 30S ribosomal subunit binding is inversely correlated with the free energy needed to unfold the 5'-UTR during mRNA accommodation into the mRNA binding cleft. Ligand binding to the riboswitch stabilizes the structure to both antagonize 30S recruitment and accelerate 30S

SUBMITTER: Ray S 

PROVIDER: S-EPMC9410914 | biostudies-literature | 2022 Aug

REPOSITORIES: biostudies-literature