RNA Innovation Seminar: Irina Artsimovitch, Ohio State University

“Locking Rho up”
Irina Artsimovitch, Ph.D.

Arts & Sciences Distinguished Professor
Department of Microbiology
The Ohio State University

In-person: BSRB, ABC seminar rooms / hybrid link

Abstract: Bacterial termination factor Rho co-transcriptionally surveils the nascent RNA and releases damaged and junk transcripts from RNA polymerase. During rapid growth, Rho maintains the transcriptome health, but how is Rho activity modulated during dormancy or stress, conditions prevalent in natural habitats? Rho is a hexameric RNA helicase that adopts active closed-ring and inactive open-ring states, and the interconversion between these states is thought to be a key checkpoint in Rho control. I will discuss two mechanisms by which ligands that bind at Rho subunit interfaces restrain ring dynamics. The Sm-like Rof protein binds at the extended RNA-binding site of Rho, occluding its RNA- and RNA polymerase-binding sites and locking the hexamer open.  The stress alarmone (p)ppGpp binds to the ATP-binding site and stabilizes the open ring, triggering phase separation into inactive higher-order oligomers and extended filaments. These and other anti-termination mechanisms are expected to silence Rho under conditions when unrestrained termination would be lethal.

Keywords: transcription; termination; Rho helicase; stress response; phase separation