The hidden life of microtubules
Cell division demands a remarkable combination of strength and flexibility. Chromosomes must remain securely attached to structures that are simultaneously growing, shrinking, and reorganising. Microtubules, hollow protein tubes within the cytoskeleton, are uniquely suited to this task. Despite their tiny size, they are among the stiffest structures in the cell, yet their ends are in constant flux. How these contradictory properties coexist has long been a puzzle in cell biology.
Vlad and his team
Theme: Molecules of Life
Centre: Molecular Cell Biology
Cells in our bodies face many challenges, including the need to be mechanically resilient; yet they also constantly remodel themselves to move and divide. Meeting these two goals is difficult – how does one keep strong and yet adaptable? Happily, the cytoskeleton – a network of cellular filaments – has evolved to do precisely that.
Microtubules are a key component of the eukaryotic cytoskeleton; they are tiny hollow tubes built from a protein called tubulin. The cylindrical shape helps microtubules to be remarkably strong. While being only 25 nm in diameter (that’s 25 millionths of a millimeter!), they are 100 times stiffer than any other component of the cytoskeleton, in real-life terms, they are as strong as plexiglass!
While a microtubule’s stiffness already looks impressive, its other important property is its ability to grow and shorten. Thanks to their remarkable dynamicity, microtubules help the cells to divide by pulling on chromosomes with their ends.
This is a critical part of biology, so SBBS undergraduates learn about properties of microtubules in their 1st year modules.
“End-attachment” is the most enigmatic property of the microtubules: how can chromosomes hold on to something that falls apart? If we imagine a chromosome as a hand that holds a rope – a microtubule – what keeps the rope from slipping through the fingers?
A recent paper published by the Volkov lab at SBBS reveals the mechanism behind this enigmatic property. Collaborating with theoretical biophysicists, they found the key structural difference between the ends of growing and shortening microtubule ends. A small change in the ability of tubulin to form sideways connections to its neighbours within the microtubule end was found to dramatically change the properties of the whole microtubule filament. This work was published in 2025 in prestigious journal PNAS (1).
What do these findings mean for the role of microtubule in cell division? This new discovery opens up a lot of important new research questions, and Filip Roch, Biochemistry BSc student, is looking at this for his final year research project with the Volkov lab. Filip is using an approach called Coarse-Grained Molecular Dynamic Simulations to find out how proteins that bind microtubule ends and chromosomes do their job. This is a theoretical biology approach where a structure of a protein is represented in a simplified form, as balls and sticks. This approach allows us to follow each protein molecule very precisely in space and time, with resolution that is experimentally unachievable. Filip compares his theoretical results to lower-resolution experimental results obtained in Volkov group (2) to find out how healthy cells divide their genomes.
Dr Vladimir Volkov is a reader in Biochemistry, and part of the Centre for Molecular Cell Biology
- Kalutskii, M., Grubmüller, H., Volkov, V.A. and Igaev, M., 2025. Microtubule dynamics are defined by conformations and stability of clustered protofilaments. Proceedings of the National Academy of Sciences, 122(22), p.e2424263122. {link}
- Radhakrishnan RM, Stokes L, Day M, Huis in ‘t Veld PJ, Volkov VA. Microtubule end stabilisation by cooperative oligomers of Ska and Ndc80 complexes (2025) bioRxiv preprint {link}