A plant virus movement protein forms ringlike complexes with the major nucleolar protein, fibrillarin, in vitro.
A plant virus movement protein forms ringlike complexes with the major nucleolar protein, fibrillarin, in vitro.
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DOI：
10.1016/j.jmb.2007.12.039
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发表时间：
2008-02-29
影响因子：
5.6
通讯作者：
Taliansky M
中科院分区：
文献类型：
--
作者：
Canetta E;Kim SH;Kalinina NO;Shaw J;Adya AK;Gillespie T;Brown JW;Taliansky M
Fibrillarin是核仁的主要蛋白质之一，具有甲基转移酶活性，指导rRNA和snRNA的2′-O-核糖甲基化，并且是rRNA加工所必需的。植物伞病毒，花生丛簇病毒，通过韧皮部，特化的植物维管系统长距离移动的能力，已被证明严格依赖于它的蛋白质之一，ORF 3蛋白（由开放阅读框3编码的蛋白质），与原纤蛋白的相互作用。这种相互作用是必不可少的几个阶段，在花生莲座病毒的生命周期，如核仁进口的ORF 3蛋白通过卡哈尔体，重新定位的一些原纤蛋白从核仁到细胞质，和装配的细胞质的伞病毒核糖核蛋白颗粒本身所需的长距离传播的病毒和全身感染。在这里，使用原子力显微镜，我们确定这些复合物的结构为单层环状结构，直径为18-22 nm，高度为2.0 ± 0.4 nm，由几个（n = 6-8）不同的蛋白质颗粒组成。我们还估计复合物中原纤蛋白与ORF 3蛋白的摩尔比约为1：1。基于这些数据，我们提出了一个模型的原纤蛋白-ORF 3蛋白复合物的结构组织，并讨论了潜在的机制和功能的影响，也可能适用于其他病毒。
Fibrillarin, one of the major proteins of the nucleolus, has methyltransferase activity directing 2′-O-ribose methylation of rRNA and snRNAs and is required for rRNA processing. The ability of the plant umbravirus, groundnut rosette virus, to move long distances through the phloem, the specialized plant vascular system, has been shown to strictly depend on the interaction of one of its proteins, the ORF3 protein (protein encoded by open reading frame 3), with fibrillarin. This interaction is essential for several stages in the groundnut rosette virus life cycle such as nucleolar import of the ORF3 protein via Cajal bodies, relocalization of some fibrillarin from the nucleolus to cytoplasm, and assembly of cytoplasmic umbraviral ribonucleoprotein particles that are themselves required for the long-distance spread of the virus and systemic infection. Here, using atomic force microscopy, we determine the architecture of these complexes as single-layered ringlike structures with a diameter of 18–22 nm and a height of 2.0 ± 0.4 nm, which consist of several (n = 6–8) distinct protein granules. We also estimate the molar ratio of fibrillarin to ORF3 protein in the complexes as approximately 1:1. Based on these data, we propose a model of the structural organization of fibrillarin–ORF3 protein complexes and discuss potential mechanistic and functional implications that may also apply to other viruses.
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