Authors
Linh T Tran, Samson Ali, Tomoharu Matsumoto, Yosuke Yamazaki, Akihiro Narita, Makito Miyazaki, Robert C Robinson
Published in
Science advances. Volume 12. Issue 29. Pages eaeh4305. Jul 17, 2026. Epub Jul 15, 2026.
Abstract
Eukaryotic microtubules are typically 13-protofilament tubes assembled from α/β-tubulin heterodimers that combine mechanical rigidity with dynamic instability. Homologous tubulins have been identified in Asgard archaea, the closest prokaryotic relatives to eukaryotes. Here, we characterize a heterodimeric α/β-tubulin system from Heimdallarchaeales. Biochemical reconstitution shows that Heim-α/β-tubulin forms a heterodimer that undergoes guanosine 5'-triphosphate-dependent polymerization with coupled nucleotide hydrolysis. Cryo-electron microscopy reveals that the polymers are composed of four-protofilament tubules, with microtubule-like lattices formed by conserved longitudinal interfaces and ball-and-socket lateral contacts. Single-filament imaging demonstrates intrinsic kinetic polarity and dynamic instability, while liposome encapsulation shows that microtubule growth generates forces sufficient to deform membranes. Despite their reduced protofilament number, Heim-α/β-microtubules share key structural and dynamic features with eukaryotic microtubules but exhibit lower bending stiffness and polymerization force. Thus, microtubule-like polymers can form from a range of protofilament numbers, with reduced architectures potentially adapted to small cellular dimensions and lower mechanical loads. Together, our results indicate expansion in microtubule protofilament number during eukaryogenesis.
PMID:
42455893
Bibliographic data and abstract were imported from PubMed on 16 Jul 2026.
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