# The gene-regulating proteins NONO and SFPQ assemble into ordered filaments

## TL;DR

This study reveals how the proteins NONO and SFPQ form structured filaments, which may help regulate genes and repair DNA.

## Contribution

The paper presents the first cryo-EM structure of NONO/SFPQ heterooligomers forming a double-helix filament.

## Key findings

- NONO/SFPQ heterodimers assemble into double-helix filaments via coiled-coil interactions.
- Filament formation was observed in vitro and may support gene regulation and DNA repair in vivo.

## Abstract

Proteins of the Drosophila behaviour/human splicing (DBHS) family are involved in many aspects of gene regulation and maintenance like transcription, splicing and DNA repair. DBHS proteins form obligate homo- and heterodimers through interactions within a globular domain and can further dynamically oligomerise through α-helical coiled-coils, which is crucial for many functions. While the atomic structures of the dimers are established, the arrangement in higher oligomers is unknown. Here we present the structure of a filamentous NONO/SFPQ heterooligomer resolved by cryo-EM. The filaments form a double helix which is stabilized by an interdigitating network of coiled-coil interactions.

Filament formation of full-length NONO/SFPQ heterodimers was observed and structurally characterized in vitro which may provide a scaffold for gene regulation, paraspeckle formation and DNA double-strand break repair in vivo.