9HXC

CryoEM structure of Asgard AtubA/B2 microtubule

Summary for 9HXC

• Entry DOI: 10.2210/pdb9hxc/pdb
• EMDB information: 52463
• Descriptor: Asgard tubulin AtubA with residues from TEV protease cleavage site, Asgard tubulin AtubB2, GUANOSINE-5'-DIPHOSPHATE (3 entities in total)
• Functional Keywords: asgard archaea, microtubule, cryoem, cytomotive filaments, cytoskeleton, structural protein
• Biological source: Candidatus Lokiarchaeum ossiferum; More
• Total number of polymer chains: 28
• Total formula weight: 1330464.04

Authors

Wollweber, F.,Xu, J.,Ponce-Toledo, R.I.,Rodrigues-Oliveira, T.,Malit, J.J.L.,Kokhanovska, A.,Wieczorek, M.,Schleper, C.,Pilhofer, M. (deposition date: 2025-01-07, release date: 2025-04-02, Last modification date: 2025-05-14)

Primary citation

Wollweber, F.,Xu, J.,Ponce-Toledo, R.I.,Marxer, F.,Rodrigues-Oliveira, T.,Possnecker, A.,Luo, Z.H.,Malit, J.J.L.,Kokhanovska, A.,Wieczorek, M.,Schleper, C.,Pilhofer, M.
Microtubules in Asgard archaea.
Cell, 188:2451-, 2025

PubMed Abstract: Microtubules are a hallmark of eukaryotes. Archaeal and bacterial homologs of tubulins typically form homopolymers and non-tubular superstructures. The origin of heterodimeric tubulins assembling into microtubules remains unclear. Here, we report the discovery of microtubule-forming tubulins in Asgard archaea, the closest known relatives of eukaryotes. These Asgard tubulins (AtubA/B) are closely related to eukaryotic α/β-tubulins and the enigmatic bacterial tubulins BtubA/B. Proteomics of Candidatus Lokiarchaeum ossiferum showed that AtubA/B were highly expressed. Cryoelectron microscopy structures demonstrate that AtubA/B form eukaryote-like heterodimers, which assembled into 5-protofilament bona fide microtubules in vitro. The additional paralog AtubB2 lacks a nucleotide-binding site and competitively displaced AtubB. These AtubA/B2 heterodimers polymerized into 7-protofilament non-canonical microtubules. In a sub-population of Ca. Lokiarchaeum ossiferum cells, cryo-tomography revealed tubular structures, while expansion microscopy identified AtubA/B cytoskeletal assemblies. Our findings suggest a pre-eukaryotic origin of microtubules and provide a framework for understanding the fundamental principles of microtubule assembly.

PubMed: 40120574
DOI: 10.1016/j.cell.2025.02.027

Experimental method

ELECTRON MICROSCOPY (3.3 Å)