人源整合膜蛋白 VDAC1 在脂双层中的结构和门控行为。
Structure and Gating Behavior of the Human Integral Membrane Protein VDAC1 in a Lipid Bilayer.
机构信息
Department of NMR-Based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077 Göttingen, Germany.
Life Sciences and Chemistry, Jacobs University of Bremen, Campus Ring 1, 28759 Bremen, Germany.
出版信息
J Am Chem Soc. 2022 Feb 23;144(7):2953-2967. doi: 10.1021/jacs.1c09848. Epub 2022 Feb 14.
The voltage-dependent anion channel (VDAC), the most abundant protein in the outer mitochondrial membrane, is responsible for the transport of all ions and metabolites into and out of mitochondria. Larger than any of the β-barrel structures determined to date by magic-angle spinning (MAS) NMR, but smaller than the size limit of cryo-electron microscopy (cryo-EM), VDAC1's 31 kDa size has long been a bottleneck in determining its structure in a near-native lipid bilayer environment. Using a single two-dimensional (2D) crystalline sample of human VDAC1 in lipids, we applied proton-detected fast magic-angle spinning NMR spectroscopy to determine the arrangement of β strands. Combining these data with long-range restraints from a spin-labeled sample, chemical shift-based secondary structure prediction, and previous MAS NMR and atomic force microscopy (AFM) data, we determined the channel's structure at a 2.2 Å root-mean-square deviation (RMSD). The structure, a 19-stranded β-barrel, with an N-terminal α-helix in the pore is in agreement with previous data in detergent, which was questioned due to the potential for the detergent to perturb the protein's functional structure. Using a quintuple mutant implementing the channel's closed state, we found that dynamics are a key element in the protein's gating behavior, as channel closure leads to the destabilization of not only the C-terminal barrel residues but also the α2 helix. We showed that cholesterol, previously shown to reduce the frequency of channel closure, stabilizes the barrel relative to the N-terminal helix. Furthermore, we observed channel closure through steric blockage by a drug shown to selectively bind to the channel, the Bcl2-antisense oligonucleotide G3139.
电压依赖性阴离子通道(VDAC)是外线粒体膜中最丰富的蛋白质,负责将所有离子和代谢物进出线粒体。它的尺寸大于迄今为止通过魔角旋转(MAS)NMR 确定的任何β-桶结构,但小于冷冻电子显微镜(cryo-EM)的尺寸限制,因此,VDAC1 的 31 kDa 大小一直是在近天然脂质双层环境中确定其结构的瓶颈。我们使用单个二维(2D)结晶的人源 VDAC1 脂质样品,应用质子检测快速魔角旋转 NMR 光谱来确定β链的排列。将这些数据与来自自旋标记样品的长程约束、基于化学位移的二级结构预测以及以前的 MAS NMR 和原子力显微镜(AFM)数据相结合,我们以 2.2 Å 的均方根偏差(RMSD)确定了通道的结构。该结构是一个 19 股β-桶,孔内有一个 N 端α-螺旋,与以前在去污剂中的数据一致,这一数据因去污剂可能扰乱蛋白质的功能结构而受到质疑。我们使用实现通道关闭状态的五倍突变体发现,动力学是蛋白质门控行为的关键因素,因为通道关闭不仅导致 C 端桶残基不稳定,而且还导致α2 螺旋不稳定。我们表明,胆固醇以前被证明可以降低通道关闭的频率,相对于 N 端螺旋稳定了桶。此外,我们观察到通过一种药物的空间阻塞导致通道关闭,该药物被证明可以选择性地结合到通道上,即 Bcl2 反义寡核苷酸 G3139。