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bioRxiv · 10.1101/2024.03.19.585385

Structural insight into bacterial co-transcriptional translation initiation

Yokoyama, T.·Murayama, Y.·Uchikubo-Kamo, T.·Tomabechi, Y.·Nagao, A.·Suzuki, T.·Shirouzu, M.·Sekine, S.-i.
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Abstract

In bacteria, transcription and translation are tightly coupled, forming a transcription-translation complex (TTC) between RNA polymerase (RNAP) and the ribosome. As nascent mRNA emerging from RNAP is susceptible to ribonuclease digestion, undesired RNA folding, and R-loop formation, immediate TTC formation is important. Here, we report the cryo-electron microscopy structures that capture the translation initiation complex assembly on transcribing RNAP. As a short mRNA emerging from RNAP, the 30S ribosomal subunit binds the RNAP on its inter-subunit side, interacting with the mRNA 5-region and the initiator tRNA. The RNAP could relocate to the canonical mRNA-entry site of 30S, threading the mRNA into a path formed between RNAP and 30S. The subsequent 50S joining establishes a TTC. These structures illustrate the transcription-coupled translation initiation, while protecting mRNA. One-Sentence SummaryCryo-EM captures the ribosome assembly on transcribing RNA polymerase in the presence of translation initiation factors.

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Yokoyama, T., Murayama, Y., Uchikubo-Kamo, T., Tomabechi, Y., Nagao, A., Suzuki, T., Shirouzu, M., Sekine, S.-i.. 2024-03-21. Structural insight into bacterial co-transcriptional translation initiation. https://doi.org/10.1101/2024.03.19.585385

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