PT  - JOURNAL ARTICLE
AU  - Seongjin Park
AU  - Karine Prévost
AU  - Emily M. Heideman
AU  - Marie-Claude Carrier
AU  - Matthew A. Reyer
AU  - Wei Liu
AU  - Eric Massé
AU  - Jingyi Fei
TI  - Dynamic interactions between the RNA chaperone Hfq, small regulatory RNAs and mRNAs in live bacterial cells
AID  - 10.1101/2020.01.13.903641
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.01.13.903641
4099  - http://biorxiv.org/content/early/2020/01/14/2020.01.13.903641.short
4100  - http://biorxiv.org/content/early/2020/01/14/2020.01.13.903641.full
AB  - RNA binding proteins play myriad roles in controlling and regulating RNAs and RNA-mediated functions, often through simultaneous binding to other cellular factors. In bacteria, the RNA chaperone Hfq modulates post-transcriptional gene regulation. Absence of Hfq leads to the loss of fitness and compromises the virulence of bacterial pathogens. Using live-cell super-resolution imaging, we are able to distinguish Hfq binding to different sizes of cellular RNAs. We demonstrate that under normal growth conditions, Hfq exhibits widespread mRNA binding activity. Particularly, the distal face of Hfq contributes mostly to the mRNA binding in vivo. In addition, binding of Hfq to these mRNAs can recruit RNase E to promote turnover of these mRNAs in an sRNA-independent manner, providing one mechanism to release Hfq from the pre-bound mRNAs. Finally, our data indicate that sRNAs, once expressed, can either co-occupy Hfq with the mRNA or displace the mRNA from Hfq, suggesting mechanisms through which sRNAs rapidly access Hfq to induce sRNA-mediated gene regulation. Our data collectively demonstrate that Hfq dynamically changes its interactions with different RNAs in response to changes in cellular conditions.