Novel machine learning approaches for improving structural discrimination in cryo-electron tomography

项目摘要 细胞冷冻电子断层扫描（Cryo-ET）使观察细胞器成为可能， 高分子复合物在纳米分辨率与天然构象。快速增长的数量 然而，可用的Cryo-ET数据带来了沿着一些主要的分析挑战，我们将及时进行分析。 穿上这个提案。我们将设计新的数据驱动的机器学习算法，以改善结构 辨别和解决。具体而言，我们有以下具体目标：（1）我们将开发一种新的 自动编码器和迭代区域匹配（AIM）算法的图像倾斜序列的无标记对齐，以重新 构造具有改进分辨率的断层图像;（2）我们将开发一种基于显著性的自动拾取算法， 更好地检测大分子复合物，并将其与创新的2D到3D框架相结合， 提高了结构检测准确率;（3）设计了一种端到端的卷积模型， 子断层图像的聚类。该模型将产生一个初始聚类，该聚类将由一个新的子聚类进行细化。 mogram平均算法，自动降低权重的子断层图像的噪声和小的贡献;（4） 我们将使用先前报道的细菌分泌系统和线粒体进行实验评估， 显微超微结构数据集，以提高最终分辨率。实现目标1-3中的算法，我们将 开发一个用户友好的开源图形用户界面-tom，以直接使科学界受益。 -tom将与现有的软件，包括IMOD，EMAN 2和Relion进行系统的模拟比较， 和基准数据集。为了便于分发，-tom将被集成到现有的软件平台Sci- π介子和TomoMiner。我们的数据驱动算法和软件不仅将促进和加速未来 使用Cryo-ET，而且还可以很容易地用于分析现有的大量Cryo-ET数据以改进 证明我们的结构，功能和大分子复合物的空间组织的理解， 原地。

Project Summary Cellular cryo-electron tomography (Cryo-ET) has made possible the observation of cellular organelles and macromolecular complexes at nanometer resolution with native conformations. The rapid increasing amount of Cryo-ET data available however brings along some major challenges for analysis which we will timely ad- dress in this proposal. We will design novel data-driven machine learning algorithms for improving structural discrimination and resolution. In particular, we have the following specific aims: (1) We will develop a novel Autoencoder and Iterative region Matching (AIM) algorithm for marker-free alignment of image tilt-series to re- construct tomograms with improved resolution; (2) We will develop a saliency-based auto-picking algorithm for better detecting macromolecular complexes, and combine it with an innovative 2D-to-3D framework to further improve structure detection accuracy; (3) We will design an end-to-end convolutional model for pose-invariant clustering of subtomograms. This model will produce an initial clustering which will be refined by a new subto- mogram averaging algorithm that automatically down-weights subtomograms of noise and little contribution; (4) We will perform experimental evaluations by using previously reported bacterial secretion systems and mito- chondrial ultrastructures datasets to improve the final resolution. Implementing algorithms in Aims 1-3, we will develop a user-friendly open-source graphical user interface -tom to directly benefit the scientific community. -tom will be systematically compared with existing software including IMOD, EMAN2, and Relion on simulated and benchmark datasets. To facilitate distribution, -tom will be integrated into existing software platforms Sci- pion and TomoMiner. Our data-driven algorithms and software not only will facilitate and accelerate the future use of Cryo-ET, but also can be readily used on analyzing the existing large amounts of Cryo-ET data to im- prove our understanding of the structure, function, and spatial organization of macromolecular complexes in situ.