6ugd
From Proteopedia
Katanin hexamer in the spiral conformation in complex with substrate
Structural highlights
Function[KTNA1_CAEEL] Catalytic subunit of a complex which severs microtubules in an ATP-dependent manner. Microtubule severing may promote rapid reorganization of cellular microtubule arrays. Required specifically for meiotic spindle formation in the female germline; the presence of this protein is inimical to the formation of mitotic spindles (PubMed:8027178, PubMed:10809666, PubMed:12885567). In body wall muscles, regulates organization of myosin thick filaments (PubMed:22621901).[HAMAP-Rule:MF_03023][1] [2] [3] [4] Publication Abstract from PubMedThe AAA ATPase katanin severs microtubules. It is critical in cell division, centriole biogenesis, and neuronal morphogenesis. Its mutation causes microcephaly. The microtubule templates katanin hexamerization and activates its ATPase. The structural basis for these activities and how they lead to severing is unknown. Here, we show that beta-tubulin tails are necessary and sufficient for severing. Cryoelectron microscopy (cryo-EM) structures reveal the essential tubulin tail glutamates gripped by a double spiral of electropositive loops lining the katanin central pore. Each spiral couples allosterically to the ATPase and binds alternating, successive substrate residues, with consecutive residues coordinated by adjacent protomers. This tightly couples tail binding, hexamerization, and ATPase activation. Hexamer structures in different states suggest an ATPase-driven, ratchet-like translocation of the tubulin tail through the pore. A disordered region outside the AAA core anchors katanin to the microtubule while the AAA motor exerts the forces that extract tubulin dimers and sever the microtubule. Katanin Grips the beta-Tubulin Tail through an Electropositive Double Spiral to Sever Microtubules.,Zehr EA, Szyk A, Szczesna E, Roll-Mecak A Dev Cell. 2019 Nov 8. pii: S1534-5807(19)30854-8. doi:, 10.1016/j.devcel.2019.10.010. PMID:31735665[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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