6p07
Spastin hexamer in complex with substrateSpastin hexamer in complex with substrate
Structural highlights
Function[A0A126GV13_DROME] ATP-dependent microtubule severing protein. Stimulates microtubule minus-end depolymerization and poleward microtubule flux in the mitotic spindle. Regulates microtubule stability in the neuromuscular junction synapse. Involved in lipid metabolism by regulating the size and distribution of lipid droplets. Involved in axon regeneration by regulating microtubule severing.[HAMAP-Rule:MF_03021] Publication Abstract from PubMedThe AAA+ ATPase spastin remodels microtubule arrays through severing and its mutation is the most common cause of hereditary spastic paraplegias (HSP). Polyglutamylation of the tubulin C-terminal tail recruits spastin to microtubules and modulates severing activity. Here, we present a ~3.2 A resolution cryo-EM structure of the Drosophila melanogaster spastin hexamer with a polyglutamate peptide bound in its central pore. Two electropositive loops arranged in a double-helical staircase coordinate the substrate sidechains. The structure reveals how concurrent nucleotide and substrate binding organizes the conserved spastin pore loops into an ordered network that is allosterically coupled to oligomerization, and suggests how tubulin tail engagement activates spastin for microtubule disassembly. This allosteric coupling may apply generally in organizing AAA+ protein translocases into their active conformations. We show that this allosteric network is essential for severing and is a hotspot for HSP mutations. An allosteric network in spastin couples multiple activities required for microtubule severing.,Sandate CR, Szyk A, Zehr EA, Lander GC, Roll-Mecak A Nat Struct Mol Biol. 2019 Jul 8. pii: 10.1038/s41594-019-0257-3. doi:, 10.1038/s41594-019-0257-3. PMID:31285604[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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