9na8 | pdb_00009na8

Augmin1345 Extended-body

spinqualitylabelsall models 9na8, resolution 3.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9na8 is a 4 chain structure with sequence from Aequorea victoria and Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.5Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function AUG1_ARATH Involved in microtubules reorganization during spindle and phragmoplast development. Publication Abstract from PubMed Microtubule (MT) branch nucleation is fundamental for building parallel MT networks in eukaryotic cells. In plants and metazoans, MT branch nucleation requires Augmin and NEDD1 proteins which bind along MTs and then recruit and activate the gamma-tubulin ring complex (gamma-TuRC). Augmin is a fork-shaped assembly composed of eight coiled-coil subunits, while NEDD1 is a WD40 beta-propellor protein that bridges across MTs, Augmin, and gamma-TuRC during MT branch nucleation. Here, we reconstitute hetero-tetrameric and hetero-octameric Arabidopsis thaliana Augmin assemblies, resolve their subunit interactions using crosslinking mass spectrometry and determine 3.7 to 7.3-A cryo-EM structures for the V-junction and extended regions of Augmin. These structures allowed us to generate a complete de novo plant Augmin model that reveals the long-range multi coiled-coil interfaces that stabilize its 40-nm hetero-octameric fork-shaped organization. We discovered the dual calponin homology (CH) domain forming its MT binding site at the end of its V-junction undertake open and closed conformations. We determined a 12-A dimeric Augmin cryo-EM structure revealing Augmin undergoes anti-parallel dimerization through two conserved surfaces along Augmin's extended region. We reconstituted the NEDD1 WD40 beta-propellor with Augmin revealing it directly binds on top its V-junction and enhances Augmin dimerization. Our studies suggest that cooperativity between the Augmin dual CH domains and NEDD1 WD40 binding site may regulate Augmin V-junction dual binding to MT lattices. This unique V-shaped dual binding and organization anchors Augmins along MTs generating a platform to recruit gamma-TuRC and activate branched MT nucleation. Cryo-EM structures of the Plant Augmin reveal its intertwined coiled-coil assembly, antiparallel dimerization and NEDD1 binding mechanisms.,Ashaduzzaman M, Taheri A, Lee YJ, Tang Y, Guo F, Fried SD, Liu B, Al-Bassam J bioRxiv [Preprint]. 2025 Feb 27:2025.02.25.640204. doi: , 10.1101/2025.02.25.640204. PMID:40034650 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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