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

Using a combination of crystallography, SAXS and cryo-EM, the katanin hexamer is observed in spiral or ring arrangements, suggesting a mechanism to generate the power stroke to severe microtubules. Microtubule-severing enzymes katanin, spastin and fidgetin are AAA ATPases important for the biogenesi...

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Bibliographic Details
Published inNature structural & molecular biology Vol. 24; no. 9; pp. 717 - 725
Main Authors Zehr, Elena, Szyk, Agnieszka, Piszczek, Grzegorz, Szczesna, Ewa, Zuo, Xiaobing, Roll-Mecak, Antonina
Format Journal Article
LanguageEnglish
Published New York Nature Publishing Group US 01.09.2017
Nature Publishing Group
Subjects
60 APPLIED LIFE SCIENCES
631/535/1258/1259
631/535/1261
631/535/1266
631/80/128/2343
82
Adenosine Triphosphatases - chemistry
Adenosine Triphosphatases - metabolism
Adenosine Triphosphatases - ultrastructure
Adenosine Triphosphate - metabolism
Animals
ATPases
Axons
BASIC BIOLOGICAL SCIENCES
Biochemistry
Biological Microscopy
Caenorhabditis elegans - enzymology
Cilia
Cryoelectron Microscopy
Crystal structure
Crystallography, X-Ray
Enzymes
Gating
Interfaces
Katanin
Life Sciences
Membrane Biology
Microtubules
Models, Molecular
Protein Binding
Protein Conformation
protein SAXS
Protein Structure
Ring structures
Spindles
Stroke
Structural members
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Summary:Using a combination of crystallography, SAXS and cryo-EM, the katanin hexamer is observed in spiral or ring arrangements, suggesting a mechanism to generate the power stroke to severe microtubules. 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.
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AC02-06CH11357
USDOE Office of Science (SC), Basic Energy Sciences (BES)
AUTHOR CONTRIBUTIONS
E.Z. prepared grids, collected and processed EM data with input from A.R.-M. The high-resolution dataset was collected at Janelia Research Campus (Howard Hughes Medical Institute). All EM data were processed on the Biowulf cluster at the National Institutes of Health. A.R.-M. and E.Z. built and refined models. A.S. purified proteins, obtained crystals, collected X-ray diffraction and SAXS data and performed ATP binding and ATP hydrolysis assays. G.P. performed and interpreted AUC. E.W. performed in vitro severing assays. X.Z. collected and processed SAXS data. A.R.-M. refined X-ray structure. A.R.-M. and E.Z. wrote manuscript. All authors reviewed the manuscript. A.R.-M. conceived project and supervised research.
ISSN:1545-9993
1545-9985
1545-9985
DOI:10.1038/nsmb.3448