Force- and length-dependent catastrophe activities explain interphase microtubule organization in fission yeast

Area of Science:

• Cell Biology
• Biophysics
• Microbiology

Background:

• The eukaryotic cytoskeleton maintains cell shape and directs growth.
• In fission yeast (Schizosaccharomyces pombe), actin organizes polarized growth, while microtubules (MTs) dictate growth location.
• MT catastrophes at cell poles limit growth to these sites.

Purpose of the Study:

• To quantitatively model microtubule (MT) catastrophe localization in Schizosaccharomyces pombe.
• To investigate the role of force-dependent MT dynamics in regulating cell polarity.
• To determine if MTs and associated proteins are sufficient for marking cell poles.

Main Methods:

• In vitro analysis of MT dynamics modulation by forces.
• Development of a computational model incorporating length-dependent catastrophe rates.
• Analysis of MT-cortex contact times and MT curling behavior in tea1Delta cells.

Main Results:

• In vitro force-dependent MT dynamics can quantitatively explain MT catastrophe localization.
• Incorporating length-dependent catastrophe rates improved model consistency with experimental data.
• The model successfully explains MT-cortex contact time distributions and MT curling.

Conclusions:

• MT dynamics, modulated by forces and length-dependent catastrophe rates, accurately predict MT catastrophe localization in fission yeast.
• MTs and depolymerizing kinesins are sufficient to mark cell poles, establishing cell polarity.
• This model provides a quantitative framework for understanding MT-based spatial regulation in cell division.