A Novel RNA Polymerase-binding Protein that interacts with a Sigma-Factor Docking Site

Anna F Wang Erickson, Padraig Deighan, Shanshan Chen, Kelsey Barrasso, Cinthia P Garcia, Santiago Martínez-Lumbreras, Caterina Alfano, Ewelina M Krysztofinska, Arjun Thapaliya, Amy H Camp, Rivka L Isaacson, Ann Hochschild, Richard Losick

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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. This article is protected by copyright. All rights reserved.

Original languageEnglish
JournalMolecular Microbiology
Early online date19 Jun 2017
Publication statusE-pub ahead of print - 19 Jun 2017


  • Journal Article


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