小柯机器人

英国约克大学Alfred A. Antson等研究人员合作绘制出一种人类肠道病毒的结构图谱。该项研究成果于2023年5月3日在线发表在《自然》杂志上。

研究人员提出了Bacteroides intestinalis病毒ΦcrAss001的冷冻电镜重建，为其大多数病毒蛋白的功能分配提供了结构基础。枪口蛋白在尾巴末端形成一个大小约为1 MDa的组件，并表现出一种以前未知的折叠，研究人员将其命名为“crass折叠”，它可能作为一个守门员，控制货物的射出。除了包装大约103kb的病毒DNA外，ΦcrAss001病毒在外壳和不寻常的尾部内有大量储存病毒编码的货物蛋白的空间。其中一个货物蛋白同时存在于帽状体和尾巴中，这表明有一种普遍的蛋白质排出机制，这涉及到蛋白质在通过尾巴挤出时的部分解折叠。这些发现为理解这些高度丰富的粗病毒的组装和感染机制提供了结构基础。

据悉，CrAssphage和Crassvirales目的相关病毒（即crassvirus）最初是通过元基因组序列的交叉组合发现的。它们是人类肠道中最丰富的病毒，在大多数个体的肠道病毒群中都有发现，在一些个体中占到了高达95%的病毒序列。crassvirus可能在塑造人类微生物组的组成和功能方面有重要作用，但大多数病毒编码蛋白的结构和作用是未知的，只有生物信息学分析得出的一般性预测。

附：英文原文

Title: Structural atlas of a human gut crassvirus

Author: Bayfield, Oliver W., Shkoporov, Andrey N., Yutin, Natalya, Khokhlova, Ekaterina V., Smith, Jake L. R., Hawkins, Dorothy E. D. P., Koonin, Eugene V., Hill, Colin, Antson, Alfred A.

Issue&Volume: 2023-05-03

Abstract: CrAssphage and related viruses of the order Crassvirales (hereafter referred to as crassviruses) were originally discovered by cross-assembly of metagenomic sequences. They are the most abundant viruses in the human gut, are found in the majority of individual gut viromes, and account for up to 95% of the viral sequences in some individuals1,2,3,4. Crassviruses are likely to have major roles in shaping the composition and functionality of the human microbiome, but the structures and roles of most of the virally encoded proteins are unknown, with only generic predictions resulting from bioinformatic analyses4,5. Here we present a cryo-electron microscopy reconstruction of Bacteroides intestinalis virus ΦcrAss0016, providing the structural basis for the functional assignment of most of its virion proteins. The muzzle protein forms an assembly about 1MDa in size at the end of the tail and exhibits a previously unknown fold that we designate the ‘crass fold’, that is likely to serve as a gatekeeper that controls the ejection of cargos. In addition to packing the approximately 103kb of virus DNA, the ΦcrAss001 virion has extensive storage space for virally encoded cargo proteins in the capsid and, unusually, within the tail. One of the cargo proteins is present in both the capsid and the tail, suggesting a general mechanism for protein ejection, which involves partial unfolding of proteins during their extrusion through the tail. These findings provide a structural basis for understanding the mechanisms of assembly and infection of these highly abundant crassviruses.

DOI: 10.1038/s41586-023-06019-2

Source: https://www.nature.com/articles/s41586-023-06019-2

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