Active transcription-translation coupling at the early translation elongation stages
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| Year of publication | 2022 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | In Bacteria and Archaea, mRNAs are translated by ribosomes simultaneously as they are transcribed. The physically coupled transcription and translation (CTT) mechanism was confirmed and visualized by cryo-electron microscopy (cryo-EM). The biochemical studies confirmed the synchronous rates of transcription and translation in E. coli suggesting a regulatory function of the leading ribosome on the RNAP propagation. However, the in-vitro cryo-EM structures show stationary CTT complexes bridged by transcription factors NusG alone or in combination with NusA. These CTT complexes lack the involvement of translation elongation factors such as EF-Tu or EF-G to activate translation phase in CTT. Here we present biochemical and cryo-EM evidence of physically interacting bacterial 70S ribosome and RNA polymerase (RNAP). The sucrose gradient binding assays confirm the presence of RNAP in the elution peak of 70S ribosome with bound nucleic acid scaffold. The initial cryo-EM map reconstruction of the CTT complex shows poor RNAP occupancy due to its dynamic behaviour. Future studies are aimed to capture the early elongation steps of CTT using EF-Tu and GTP in a time-dependent manner. Time-resolved cryo-EM approach will enable the investigation of active transcription-translation coupling via EF-Tu initiated translation elongation process. |
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