National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Disease (NIH/NIDDK)
NIH DK 027044
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
NIH GM 110530
米国
引用
ジャーナル: Proc Natl Acad Sci U S A / 年: 2022 タイトル: Munc13 structural transitions and oligomers that may choreograph successive stages in vesicle priming for neurotransmitter release. 著者: Kirill Grushin / R Venkat Kalyana Sundaram / Charles V Sindelar / James E Rothman / 要旨: How can exactly six SNARE complexes be assembled under each synaptic vesicle? Here we report cryo-EM crystal structures of the core domain of Munc13, the key chaperone that initiates SNAREpin ...How can exactly six SNARE complexes be assembled under each synaptic vesicle? Here we report cryo-EM crystal structures of the core domain of Munc13, the key chaperone that initiates SNAREpin assembly. The functional core of Munc13, consisting of C1-C2B-MUN-C2C (Munc13C) spontaneously crystallizes between phosphatidylserine-rich bilayers in two distinct conformations, each in a radically different oligomeric state. In the open conformation (state 1), Munc13C forms upright trimers that link the two bilayers, separating them by ∼21 nm. In the closed conformation, six copies of Munc13C interact to form a lateral hexamer elevated ∼14 nm above the bilayer. Open and closed conformations differ only by a rigid body rotation around a flexible hinge, which when performed cooperatively assembles Munc13 into a lateral hexamer (state 2) in which the key SNARE assembly-activating site of Munc13 is autoinhibited by its neighbor. We propose that each Munc13 in the lateral hexamer ultimately assembles a single SNAREpin, explaining how only and exactly six SNARE complexes are templated. We suggest that state 1 and state 2 may represent two successive states in the synaptic vesicle supply chain leading to "primed" ready-release vesicles in which SNAREpins are clamped and ready to release (state 3).
使用したクラス数: 8 / 想定した対称性 - 点群: C1 (非対称) / 解像度のタイプ: BY AUTHOR / 解像度: 10.0 Å / 解像度の算出法: OTHER / ソフトウェア - 名称: RELION (ver. 3.1) 詳細: Combined map of best classes from two 3D classifications in RELION 3.1 of selected regions without angular searches using C6 symmetry expanded dataset. 使用したサブトモグラム数: 72894
抽出
トモグラム数: 62 / 使用した粒子像数: 36837 詳細: Particles were extracted and refined using Warp/M software
最終 角度割当
タイプ: MAXIMUM LIKELIHOOD / ソフトウェア - 名称: RELION (ver. 3.1)
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原子モデル構築 1
詳細
Model for fitting was generated by AlphaFold using the construct's amino acid sequence. Flexible fitting into 3D map densities was performed using ISOLDE tool in ChimeraX.
精密化
プロトコル: FLEXIBLE FIT
得られたモデル
PDB-7t7v: Munc13-1 C1-C2B-MUN-C2C Lateral conformation on lipid bilayer surface