Kinesin Kip2 enhances microtubule growth in vitro through length-dependent feedback on polymerization and catastrophe
Anneke Hibbel,
Aliona Bogdanova,
Mohammed Mahamdeh,
Anita Jannasch,
Marko Storch,
Erik Schäffer,
Dimitris Liakopoulos,
Jonathon Howard
Affiliations
Anneke Hibbel
Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany; Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
Aliona Bogdanova
Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
Mohammed Mahamdeh
Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, United States
Anita Jannasch
Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany; Zentrum für Molekularbiologie der Pflanzen, Eberhard-Karls-Universität, Tübingen, Germany
Marko Storch
Department of Life Sciences, Imperial College London, London, United Kingdom
Erik Schäffer
Zentrum für Molekularbiologie der Pflanzen, Eberhard-Karls-Universität, Tübingen, Germany
Dimitris Liakopoulos
CRBM-CRNS, Montpellier, France
Jonathon Howard
Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, United States
The size and position of mitotic spindles is determined by the lengths of their constituent microtubules. Regulation of microtubule length requires feedback to set the balance between growth and shrinkage. Whereas negative feedback mechanisms for microtubule length control, based on depolymerizing kinesins and severing proteins, have been studied extensively, positive feedback mechanisms are not known. Here, we report that the budding yeast kinesin Kip2 is a microtubule polymerase and catastrophe inhibitor in vitro that uses its processive motor activity as part of a feedback loop to further promote microtubule growth. Positive feedback arises because longer microtubules bind more motors, which walk to the ends where they reinforce growth and inhibit catastrophe. We propose that positive feedback, common in biochemical pathways to switch between signaling states, can also be used in a mechanical signaling pathway to switch between structural states, in this case between short and long polymers.
