Coupling and Uncoupling Transcription with Translation
We show that transcription and translation are physically coupled in E.coli by the NusG protein. The NTD of NusG binds RNAP, whereas its CTD binds ribosomal protein S10. We present a cryo-EM structure showing NusG CTD bound to S10 in an intact 70S ribosome. We find that NusG is required for coupling in vivo. Amino acid starvation induces uncoupling and consequent Rho-dependent intragenic transcription termination. Uncoupling is promoted by tmRNA, which both releases stalled ribosomes and competes with NusG for binding to S10.
Inhibiting translation early in a gene prevents coupling, suggesting a lag in loading NusG.
Columbia University, New York, USA
Domain 1 - UMR 3348 - Genotoxic Stress and Cancer