Tilt-series-based joint CTF estimation for cryo-electron tomography

IF 4.4 2区生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY

Structure Pub Date : 2024-05-31 DOI:10.1016/j.str.2024.05.006

Ranhao Zhang, Yuan Shen, Xueming Li

引用次数: 0

Abstract

Contrast transfer function (CTF) estimation is a necessary step in the cryo-electron tomography (cryoET) workflow and essential for high-resolution in situ structural determination. However, the low signal-to-noise ratio and continuous defocus variation in micrographs of cryoET tilt series make accurate CTF estimation challenging. Here, we report a tilt-series-based joint CTF estimation method implemented in the new software CTFMeasure. The joint estimation method combines all Thon-ring signals in a tilt series to improve the estimation accuracy. By using an objective function involving the CTF parameters and geometric parameters of a cryoET tilt series, CTFMeasure can estimate the CTF parameters of each micrograph and the absolute tilt angle offset of the lamellar sample relative to the sample stage plane, which is usually the glancing angle used during focused ion beam (FIB) milling. Tests on both synthetic and experimental data, as well as subtomogram averaging, demonstrated the accurate CTF estimation of cryoET tilt series by CTFMeasure.

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基于倾斜序列的低温电子断层扫描联合 CTF 估算

对比传递函数（CTF）估算是低温电子断层成像（cryoET）工作流程的必要步骤，也是高分辨率原位结构测定的关键。然而，低温电子层析成像倾斜序列显微照片的信噪比低和连续离焦变化使得准确的对比传递函数估计具有挑战性。在此，我们报告了一种基于倾斜序列的联合 CTF 估算方法，该方法已在新软件 CTFMeasure 中实现。这种联合估算方法结合了倾斜序列中的所有通环信号，从而提高了估算精度。通过使用涉及 CTF 参数和 cryoET 倾斜系列几何参数的目标函数，CTFMeasure 可以估算出每张显微照片的 CTF 参数以及片状样品相对于样品台平面的绝对倾斜角偏移，这通常是聚焦离子束 (FIB) 铣削过程中使用的闪烁角。对合成数据和实验数据以及子图平均的测试表明，CTFMeasure 能准确地估计 CryoET 倾斜系列的 CTF。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Structure 生物-生化与分子生物学

CiteScore

8.90

自引率

1.80%

发文量

155

审稿时长

3-8 weeks

期刊介绍： Structure aims to publish papers of exceptional interest in the field of structural biology. The journal strives to be essential reading for structural biologists, as well as biologists and biochemists that are interested in macromolecular structure and function. Structure strongly encourages the submission of manuscripts that present structural and molecular insights into biological function and mechanism. Other reports that address fundamental questions in structural biology, such as structure-based examinations of protein evolution, folding, and/or design, will also be considered. We will consider the application of any method, experimental or computational, at high or low resolution, to conduct structural investigations, as long as the method is appropriate for the biological, functional, and mechanistic question(s) being addressed. Likewise, reports describing single-molecule analysis of biological mechanisms are welcome. In general, the editors encourage submission of experimental structural studies that are enriched by an analysis of structure-activity relationships and will not consider studies that solely report structural information unless the structure or analysis is of exceptional and broad interest. Studies reporting only homology models, de novo models, or molecular dynamics simulations are also discouraged unless the models are informed by or validated by novel experimental data; rationalization of a large body of existing experimental evidence and making testable predictions based on a model or simulation is often not considered sufficient.

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