# The Ync13–Rga7–Rng10 complex selectively coordinates secretory vesicle trafficking and secondary septum formation during cytokinesis

## TL;DR

This study identifies a protein complex that ensures proper cell division by controlling vesicle trafficking and septum formation.

## Contribution

The discovery of a conserved Ync13-Rga7-Rng10 module that selectively coordinates vesicle tethering and fusion during cytokinesis.

## Key findings

- The Ync13-Rga7-Rng10 module recruits TRAPP-II but not the exocyst complex to tether glucan synthase-containing vesicles.
- Ync13 interacts with SM protein Sec1 to facilitate vesicle fusion at the cleavage furrow.
- Disruption of this pathway leads to defective septum formation and cell lysis.

## Abstract

Cytokinesis requires precise coordination of contractile-ring constriction, vesicle trafficking and fusion to the plasma membrane, and extracellular matrix assembly/remodeling at the cleavage furrow to ensure faithful cell division and maintain cell integrity. These processes and proteins involved are broadly conserved across eukaryotes, yet molecular mechanisms controlling the spatiotemporal pathways of membrane trafficking remain poorly understood. Here, using fission yeast genetics, microscopy, and in vitro binding assays, we identify a conserved module including the Munc13 protein Ync13, F-BAR protein Rga7, and coiled-coil protein Rng10 to be critical for precise and selective vesicle targeting to the plasma membrane during cytokinesis. The module specifically recruits the TRAPP-II but not the exocyst complex to tether vesicles containing the glucan synthases Bgs4 and Ags1 along the cleavage furrow. Ync13 subsequently interacts with the SM protein Sec1 for vesicle fusion. Mutations in this pathway disrupt septum integrity and lead to cell lysis. Our work provides key insights into how membrane trafficking is tightly controlled to maintain cell integrity during cytokinesis.

Cytokinesis relies on coordinated contractile-ring constriction, vesicle trafficking, and extracellular matrix remodeling to ensure successful cell division. This study shows that a conserved Ync13-Rga7-Rng10 module coordinates the selective tethering and fusion of vesicles containing glucan synthases at the division site, ensuring proper septum formation and cell integrity during cytokinesis.