Regulation of microtubule abundance and minus end dynamics by Katanin, CAMSAPs, WDR47 and kinesin-13

Microtubule networks are major determinants of cell architecture and logistics. Microtubule organization and density are regulated by severing enzymes, which cut microtubule lattices or affect their growth and shortening. These activities can lead to microtubule amplification or disassembly, depending on the presence of microtubule stabilizers or destabilizers, but the interplay between these factors is poorly understood. Here, we reconstituted in vitro the activity of microtubule severase katanin together with microtubule minus-end stabilizers CAMSAPs, their binding partner WDR47 and microtubule depolymerase kinesin-13/MCAK. We confirmed that katanin can amplify or destroy microtubules in a concentration-dependent manner. CAMSAPs recruit katanin to microtubules and reduce katanin concentration needed for both amplification and destruction, whereas kinesin-13 completely abolishes microtubule amplification. WDR47 binds to microtubules decorated by CAMSAPs and suppresses katanin binding and severing. In addition, both katanin and WDR47 inhibit polymerization of CAMSAP-decorated microtubule minus ends. These data explain how these proteins act together to fine-tune microtubule minus-end stability without strongly increasing microtubule abundance.