3 years ago

Katanin spiral and ring structures shed light on power stroke for microtubule severing

Katanin spiral and ring structures shed light on power stroke for microtubule severing
Ewa Szczesna, Grzegorz Piszczek, Agnieszka Szyk, Antonina Roll-Mecak, Xiaobing Zuo, Elena Zehr
Microtubule-severing enzymes katanin, spastin and fidgetin are AAA ATPases important for the biogenesis and maintenance of complex microtubule arrays in axons, spindles and cilia. Because of a lack of known 3D structures for these enzymes, their mechanism of action has remained poorly understood. Here we report the X-ray crystal structure of the monomeric AAA katanin module from Caenorhabditis elegans and cryo-EM reconstructions of the hexamer in two conformations. The structures reveal an unexpected asymmetric arrangement of the AAA domains mediated by structural elements unique to microtubule-severing enzymes and critical for their function. The reconstructions show that katanin cycles between open spiral and closed ring conformations, depending on the ATP occupancy of a gating protomer that tenses or relaxes interprotomer interfaces. Cycling of the hexamer between these conformations would provide the power stroke for microtubule severing.

Publisher URL: http://dx.doi.org/10.1038/nsmb.3448

DOI: 10.1038/nsmb.3448

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