RT Journal Article
SR Electronic
T1 Specific length and structure rather than high thermodynamic stability enable regulatory mRNA stem-loops to pause translation
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.08.16.456581
DO 10.1101/2021.08.16.456581
A1 Bao, Chen
A1 Zhu, Mingyi
A1 Nykonchuk, Inna
A1 Wakabayashi, Hironao
A1 Mathews, David H.
A1 Ermolenko, Dmitri N.
YR 2021
UL http://biorxiv.org/content/early/2021/08/17/2021.08.16.456581.abstract
AB Translating ribosomes unwind mRNA secondary structures by three basepairs each elongation cycle. Despite the ribosome helicase, certain mRNA stem-loops stimulate programmed ribosomal frameshift by inhibiting translation elongation. Here, using mutagenesis, biochemical and single-molecule experiments, we examine whether high stability of three basepairs, which are unwound by the translating ribosome, is critical for inducing ribosome pauses. We find that encountering frameshift-inducing mRNA stem-loops from the E. coli dnaX mRNA and the gag-pol transcript of Human Immunodeficiency Virus (HIV) hinders A-site tRNA binding and slows down ribosome translocation by 15-20 folds. By contrast, unwinding of first three basepairs adjacent to the mRNA entry channel slows down the translating ribosome by only 2-3 folds. Rather than high thermodynamic stability, specific length and structure enable regulatory mRNA stem-loops to stall translation by forming inhibitory interactions with the ribosome. Our data provide the basis for rationalizing transcriptome-wide studies of translation and searching for novel regulatory mRNA stem-loops.Competing Interest StatementThe authors have declared no competing interest.