# Distinct filament morphology and membrane tethering features of the dual FtsZ paralogs in Odinarchaeota

## TL;DR

This study explores two different FtsZ proteins in Odinarchaeota, revealing unique filament structures and membrane attachment methods, offering insights into the evolution of cytoskeletal proteins.

## Contribution

The study identifies distinct filament assembly and membrane tethering mechanisms for two FtsZ paralogs in Odinarchaeota, shedding light on their evolutionary divergence.

## Key findings

- OdinFtsZ1 forms single protofilaments and binds membranes via an N-terminal helix.
- OdinFtsZ2 forms stacked ring-like filaments and is anchored to membranes via SepF.
- The two FtsZ paralogs represent distant evolutionary paralogs with distinct assembly and tethering features.

## Abstract

The Asgard phylum has emerged as a model to study eukaryogenesis because of their close relatedness with the eukaryotes. In this study, we use FtsZ proteins from a member of the class Odinarchaeia as representatives to investigate the probable origin, evolution, and assembly of the FtsZ/tubulin protein superfamily in Asgard archaea. We performed a comparative analysis of the biochemical properties and cytoskeletal assembly of FtsZ1 and FtsZ2, the two FtsZ isoforms in the Odinarchaeota metagenome. Our electron microscopy analysis reveals that OdinFtsZ1 assembles into curved single protofilaments, while OdinFtsZ2 forms stacked spiral ring-like structures. Upon sequence analysis, we identified an N-terminal amphipathic helix in OdinFtsZ1, which mediates direct membrane tethering. In contrast, OdinFtsZ2 is recruited to the membrane by the anchor OdinSepF via OdinFtsZ2’s C-terminal tail. Overall, we report the presence of two distant evolutionary paralogs of FtsZ in Odinarchaeota, with distinct filament assemblies and differing modes of membrane targeting. Our findings highlight the diversity of FtsZ proteins in the archaeal phylum Asgardarchaeota, providing valuable insights into the evolution and differentiation of tubulin-family proteins.

The tubulin/FtsZ superfamily of cytoskeletal proteins may have originated in Asgard archaea. This study reveals different filament morphologies membrane tethering mechanisms for the dual FtsZ paralogs present in Odinarchaeon LCB_4, FtsZ1 and FtsZ2.

The two FtsZ paralogs of Odinarchaeon assemble into different filament morphologies.OdinFtsZ1 forms canonical single protofilaments similar to bacterial FtsZ proteins, whereas OdinFtsZ2 forms a stacked ring-like filaments.Odinarchaeon SepF functions as a membrane anchor exclusively for OdinFtsZ2.OdinFtsZ1 utilises an N-terminal amphipathic helix for direct membrane binding.

The two FtsZ paralogs of Odinarchaeon assemble into different filament morphologies.

OdinFtsZ1 forms canonical single protofilaments similar to bacterial FtsZ proteins, whereas OdinFtsZ2 forms a stacked ring-like filaments.

Odinarchaeon SepF functions as a membrane anchor exclusively for OdinFtsZ2.

OdinFtsZ1 utilises an N-terminal amphipathic helix for direct membrane binding.

Structural data show that OdinFtsZ1 filamentizes like bacterial FtsZ and binds membranes via an amphipathic helix, while stacked ring-like OdinFtsZ2 filaments are anchored via SepF.