2026-07-16 理化学研究所,名古屋大学,ウィタヤシリメティー科学技術大学院大学,岡山大学,科学技術振興機構
今回の研究で明らかにした原始的な微小管の構造と機能
＜関連情報＞
- https://www.riken.jp/press/2026/20260716_1/index.html
- https://www.science.org/doi/10.1126/sciadv.aeh4305
ヘイムダルカルカエレスα/β-チューブリン由来の4本プロトフィラメント微小管の構造とダイナミクス Structure and dynamics of a four-protofilament microtubule from Heimdallarchaeales α/β-tubulin
Linh T. Tran, Samson Ali, Tomoharu Matsumoto, Yosuke Yamazaki, […] , and Robert C. Robinson
Science Advances Published:15 Jul 2026
DOI:https://doi.org/10.1126/sciadv.aeh4305
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.
