Models are useful until high-resolution structures are available.
Models are useful until high-resolution structures are available.
复制标题
DOI：
10.1016/j.tim.2023.03.007
复制
发表时间：
2023-03
影响因子：
15.9
通讯作者：
Fengbin Wang;L. Craig;Xing Liu;C. Rensing;E. Egelman
中科院分区：
文献类型：
--
作者：
Fengbin Wang;L. Craig;Xing Liu;C. Rensing;E. Egelman
我们的综述[1]是关于由PilA-N和PilA-C形成的地质杆菌T4P的冷冻电子显微镜(Cryo-EM)结构和细胞色素细丝。对此，Lovley[2]认为，有大量证据表明PilA-N单独组装成3 nm的细丝，但由于未知的原因，低温电磁无法观察到这些证据。Lovley的结论是，PilA-N单独产生导电细丝严重依赖于原子力显微镜(AFM)测量，他相信3 nm AFM直径可以定义细丝的组成。测量的直径与他发表的PilA-N细丝的模型[3]相矛盾，该模型的实际直径为~6.0 nm。然而，他的AFM成像无法准确测量纤维直径，也无法解析这些风干纤维中的任何结构或周期性。我们从80多年的结构生物学中知道，蛋白质只有在水溶液或溶液中的晶体中才能完全水合[4]。AFM对一种基于DNA的结构的检测发现，其在液体中的尺寸与风干时的尺寸相差2倍[5]。
Our review [1] was about cryo-electron microscopy (cryo-EM) structures of Geobacter T4P, formed by PilA-N and PilA-C, and cytochrome filaments. In response, Lovley [2] argues that abundant evidence exists for PilA-N alone assembling into 3-nm filaments, that, for unknown reasons, are not seen by cryo-EM.Lovley’s conclusion that PilA-N alone produces conductive filaments relies heavily upon atomic force microscopy (AFM) measurements, and he believes that the 3-nm AFM diameter can define the composition of filaments. The measured diameter conflicts with his published model for a PilA-N filament [3], which had an actual diameter of~ 6.0 nm. However, his AFM imaging does not accurately measure filament diameter and fails to resolve any structure or periodicity within these air-dried filaments. We know from more than 80 years of structural biology that proteins are only fully hydrated when they are in aqueous solution or in a crystal in solution [4]. An AFM examination of a DNA-based structure found a factor of 2 difference between its dimensions in liquid and when air-dried [ 5].