Structural state recognition facilitates tip tracking of EB1 at growing microtubule ends
Taylor A Reid,
Courtney Coombes,
Soumya Mukherjee,
Rebecca R Goldblum,
Kyle White,
Sneha Parmar,
Mark McClellan,
Marija Zanic,
Naomi Courtemanche,
Melissa K Gardner
Affiliations
Taylor A Reid
Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
Courtney Coombes
Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
Soumya Mukherjee
Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
Rebecca R Goldblum
Medical Scientist Training Program, University of Minnesota, Minneapolis, United States; Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, United States
Kyle White
Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
Sneha Parmar
Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
Mark McClellan
Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
The microtubule binding protein EB1 specifically targets the growing ends of microtubules in cells, where EB1 facilitates the interactions of cellular proteins with microtubule plus-ends. Microtubule end targeting of EB1 has been attributed to high-affinity binding of EB1 to GTP-tubulin that is present at growing microtubule ends. However, our 3D single-molecule diffusion simulations predicted a ~ 6000% increase in EB1 arrivals to open, tapered microtubule tip structures relative to closed lattice conformations. Using quantitative fluorescence, single-molecule, and electron microscopy experiments, we found that the binding of EB1 onto opened, structurally disrupted microtubules was dramatically increased relative to closed, intact microtubules, regardless of hydrolysis state. Correspondingly, in cells, the blunting of growing microtubule plus-ends by Vinblastine was correlated with reduced EB1 targeting. Together, our results suggest that microtubule structural recognition, based on a fundamental diffusion-limited binding model, facilitates the tip tracking of EB1 at growing microtubule ends.
