PT  - JOURNAL ARTICLE
AU  - Robert S. Washburn
AU  - Philipp K. Zuber
AU  - Ming Sun
AU  - Yaser Hashem
AU  - Bingxin Shen
AU  - Wen Li
AU  - Sho Harvey
AU  - Stefan H. Knauer
AU  - Joachim Frank
AU  - Max E. Gottesman
TI  - <em>Escherichia coli</em> NusG links the lead ribosome with the transcription elongation complex
AID  - 10.1101/871962
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 871962
4099  - http://biorxiv.org/content/early/2019/12/11/871962.short
4100  - http://biorxiv.org/content/early/2019/12/11/871962.full
AB  - It has been known for more than 50 years that transcription and translation are physically coupled in bacteria, but whether or not this coupling may be mediated by the two-domain protein N-utilization substance (Nus) G in Escherichia coli is still heavily debated. Here, we combine integrative structural biology and functional analyses to provide conclusive evidence that NusG can physically link transcription with translation by contacting both RNA polymerase and the ribosome. We present a cryo-electron microscopy structure of a NusG:70S ribosome complex and nuclear magnetic resonance spectroscopy data revealing simultaneous binding of NusG to RNAP and the intact 70S ribosome, providing the first direct structural evidence for NusG-mediated coupling. Furthermore, in vivo reporter assays show that recruitment of NusG occurs late in transcription and strongly depends on translation. Thus, our data suggest that coupling occurs initially via direct RNAP:ribosome contacts and is then mediated by NusG.