A novel RNA polymerase-binding protein that interacts with a sigma-factor docking site.Wang Erickson, A.F., Deighan, P., Chen, S., Barrasso, K., Garcia, C.P., Martinez-Lumbreras, S., Alfano, C., Krysztofinska, E.M., Thapaliya, A., Camp, A.H., Isaacson, R.L., Hochschild, A., Losick, R.
(2017) Mol Microbiol 105: 652-662
- PubMed: 28598017
- DOI: https://doi.org/10.1111/mmi.13724
- Primary Citation of Related Structures:
- PubMed Abstract:
Sporulation in Bacillus subtilis is governed by a cascade of alternative RNA polymerase sigma factors. We previously identified a small protein Fin that is produced under the control of the sporulation sigma factor σ F to create a negative feedback loop that inhibits σ F -directed gene transcription. Cells deleted for fin are defective for spore formation and exhibit increased levels of σ F -directed gene transcription. Based on pull-down experiments, chemical crosslinking, bacterial two-hybrid experiments and nuclear magnetic resonance chemical shift analysis, we now report that Fin binds to RNA polymerase and specifically to the coiled-coil region of the β' subunit. The coiled-coil is a docking site for sigma factors on RNA polymerase, and evidence is presented that the binding of Fin and σ F to RNA polymerase is mutually exclusive. We propose that Fin functions by a mechanism distinct from that of classic sigma factor antagonists (anti-σ factors), which bind directly to a target sigma factor to prevent its association with RNA polymerase, and instead functions to inhibit σ F by competing for binding to the β' coiled-coil.
Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA.