SKM 2023 – scientific programme
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BP: Fachverband Biologische Physik
BP 23: Single Molecule Biophysics
BP 23.9: Talk
Thursday, March 30, 2023, 12:00–12:15, BAR 0106
Lattice defect sites accelerate microtubule severing by spastin — •Cordula Reuther1, Paula Santos-Otte1, Rahul Grover1, and Stefan Diez1,2,3 — 1B CUBE - Center for Molecular Bioengineering, TU Dresden, Dresden, Germany — 2Cluster of Excellence Physics of Life, TU Dresden, Dresden, Germany — 3Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
Length regulation of microtubules and their organization into complex arrays occurs through the activity of polymerases, depolymerases as well as severing enzymes such as katanin and spastin. The latter hexamerize on the microtubule lattice, pull out single tubulin dimers in an ATP-dependent manner and eventually generate internal breaks in the microtubule. For both enzymes it was shown that the severing activity is regulated by tubulin posttranslational modifications. So far, however, only katanin has been reported to exhibit a lattice-defect- or crossover-sensing activity. Here, we determined whether lattice defects in GMPCPP-stabilized microtubules also affect the severing activity by spastin. In controlled in vitro assays we characterized microtubules with defects next to control microtubules. Defect sites were introduced either through specific polymerization conditions or by end-to-end annealing of microtubules. We found that (i) the presence of defects accelerated the onset of the severing process and (ii) severing occured twice as often in microtubule segments with defect sites as compared to random lattice segments. Furthermore, we quantified the correlation of the fluorescence signal of GFP-labelled spastin along the microtubule lattice to the severing sites as a function of time.