Studying the Effects of Modified Tubulin C-Terminal Tails on Katanin Severing Activity

Abstract

Microtubule severing enzymes are AAA+ enzymes that sever microtubule filaments in order to regulate the organization of the cytoskeleton of cells. We have recently shown that katanin, the first identified sever enzyme, is inhibited by free tubulin dimers. Further, we showed that inhibition is specific for the carboxy-terminal tail and is isotype and post-translationally specific. Further, the inhibition of katanin is more potent than has been observed for spastin, a second severing enzyme, and has different reactions to different isotypes and post-translational modifications. This implies that katanin is regulated through different paths than spastin. We are currently investigation the inhibitory effects of numerous carboxy-terminal tail types. We perform in vitro reconstitution assays using wholly purified proteins and polypeptide carboxy-terminal tails of tubulin. This work provides a view into how katanin recognition of the CTT of tubulin regulates microtubule severing. A further understanding of this interaction is needed in order to understand how microtubule regulation is performed at the molecular level.