Molecular basis of mRNA delivery to the bacterial ribosome

Michael W. Webster*, Adrien Chauvier, Huma Rahil, Andrea Graziadei, Kristine Charles, Nataliya Miropolskaya, Maria Takacs, Charlotte Saint-André, Juri Rappsilber, Nils G. Walter, Albert Weixlbaumer*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Protein synthesis begins with the formation of a ribosome-messenger RNA (mRNA) complex. In bacteria, the small ribosomal subunit (30S) is recruited to many mRNAs through base pairing with the Shine-Dalgarno (SD) sequence and RNA binding by ribosomal protein bS1. Translation can initiate on nascent mRNAs, and RNA polymerase (RNAP) can promote the recruitment of the pioneering 30S. Here, we examined 30S recruitment to nascent mRNAs using cryo?electron microscopy, single-molecule fluorescence colocalization, and in-cell cross-linking mass spectrometry. We show that bS1 delivers the mRNA to the ribosome for SD duplex formation and 30S activation. Additionally, bS1 and RNAP stimulate translation initiation. Our work provides a mechanistic framework for how the SD duplex, ribosomal proteins, and RNAP cooperate in 30S recruitment to mRNAs and establish transcription-translation coupling. To express a protein-coding gene, RNA polymerase transcribes DNA into mRNA, and the ribosome subsequently translates the mRNA to a protein. In bacteria, transcription and translation occur simultaneously, and this enables RNA polymerase and the ribosome to cooperate with each other. Using cryo?electron microscopy, Webster et al. visualized the early encounter between a transcribing RNA polymerase and a ribosome, which initiates translation on the nascent mRNA. Supported by single-molecule experiments and in-cell cross-linking mass spectrometry, this study shows how the different elements of the two machineries cooperate to recruit a ribosome to a nascent mRNA. ?Di Jiang
Original languageEnglish
Pages (from-to)eado8476
Number of pages17
JournalScience
Volume386
Issue number6725
DOIs
Publication statusPublished - 29 Nov 2024

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