RNA modifications and structures cooperate to guide RNA-protein interactions.

An emerging body of evidence indicates that post-transcriptional gene regulation relies not only on the sequence of mRNAs but also on their folding into intricate secondary structures and on the chemical modifications of the RNA bases. These features, which are highly dynamic and interdependent, exert direct control over the transcriptome and thereby influence many aspects of cell function. Here, we consider how the coupling of RNA modifications and structures shapes RNA-protein interactions at different steps of the gene expression process.

Quantitative profiling of human translation initiation reveals regulatory elements that potently affect endogenous and therapeutically modified mRNAs.

mRNA therapeutics offer a potentially universal strategy for the efficient development and delivery of therapeutic proteins. Current mRNA vaccines include chemically modified nucleotides to reduce cellular immunogenicity. Here, we develop an efficient, high-throughput method to measure human translation initiation on therapeutically modified as well as endogenous RNAs. Using systems-level biochemistry, we quantify ribosome recruitment to tens of thousands of human 5' untranslated regions and identify sequences that mediate 250-fold effects. We observe widespread effects of coding sequences on translation initiation and identify small regulatory elements of 3-6 nucleotides that are sufficient to potently affect translational output. Incorporation of N1-methylpseudouridine (m1Ψ) selectively enhances translation by specific 5' UTRs that we demonstrate surpass those of current mRNA vaccines. Our approach is broadly applicable to dissect mechanisms of human translation initiation and engineer more potent therapeutic mRNAs. Highlights: Measurement of >30,000 human 5' UTRs reveals a 250-fold range of translation outputSystematic mutagenesis demonstrates the causality of short (3-6nt) regulatory elementsN1-methylpseudouridine alters translation initiation in a sequence-specific mannerOptimal modified 5' UTRs outperform those in the current class of mRNA vaccines.

Optimized protocol for quantifying 5' UTR-mediated translation initiation in S. cerevisiae using direct analysis of ribosome targeting.

Direct analysis of ribosome targeting (DART) allows investigators to measure the translation initiation potential of thousands of RNAs in parallel. Here, we describe an optimized protocol for generating active translation extract from S. cerevisiae, followed by in vitro translation, purification of ribosome-bound RNAs, and subsequent library preparation and sequencing. This protocol can be applied to a variety of cell types and will enable high-throughput interrogation of translational determinants. For complete details on the use and execution of this protocol, please refer to Niederer et al. (2022).1.