# A family of bacterial actin homologs forms a three-stranded tubular structure

## TL;DR

Scientists discovered a new type of bacterial actin that forms a three-stranded tube, offering insights into bacterial cytoskeleton diversity and evolution.

## Contribution

The study identifies a novel bacterial actin family forming a unique three-stranded tubular structure in the Verrucomicrobiota phylum.

## Key findings

- A conserved bacterial actin family in Verrucomicrobiota assembles into a three-stranded tubular structure with ATP.
- Cryo-EM reveals a distinct three-strand architecture unlike other bacterial actin structures.
- The findings expand understanding of bacterial cytoskeleton diversity and evolutionary adaptations.

## Abstract

The cytoskeleton is crucial for cell organization and movement. In Eukaryotes, it largely consists of the protein actin, that forms a double-stranded linear filamentous structure in the presence of ATP and disassemble upon ATP hydrolysis. Bacteria also possess actin homologs, that drive fundamental cellular processes, including cell division, shape maintenance, and DNA segregation. Like eukaryotic actin, bacterial actins assemble into dynamic polymers upon ATP binding, however variation in interactions between strands gives rise to striking diversity of filament architectures. Here, we report a family of bacterial actins of unknown function, conserved among the Verrucomicrobiota phylum, which assembles into a unique tubular structure in the presence of ATP. A cryo-EM structure of the filaments reveals that it consists of three strands, unlike other described bacterial actin structures. This architecture provides further insights into the organization of actin-like filaments and has implications for understanding the diversity and evolution of the bacterial cytoskeleton.