Ertel Kenneth J, Benefield Desirée, Castaño-Diez Daniel, Pennington Janice G, Horswill Mark, den Boon Johan A, Otegui Marisa S, Ahlquist Paul
Institute for Molecular Virology, University of Wisconsin-Madison, Madison, United States.
Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, United States.
Elife. 2017 Jun 27;6:e25940. doi: 10.7554/eLife.25940.
Positive-strand RNA viruses, the largest genetic class of viruses, include numerous important pathogens such as Zika virus. These viruses replicate their RNA genomes in novel, membrane-bounded mini-organelles, but the organization of viral proteins and RNAs in these compartments has been largely unknown. We used cryo-electron tomography to reveal many previously unrecognized features of Flock house nodavirus (FHV) RNA replication compartments. These spherular invaginations of outer mitochondrial membranes are packed with electron-dense RNA fibrils and their volumes are closely correlated with RNA replication template length. Each spherule's necked aperture is crowned by a striking cupped ring structure containing multifunctional FHV RNA replication protein A. Subtomogram averaging of these crowns revealed twelve-fold symmetry, concentric flanking protrusions, and a central electron density. Many crowns were associated with long cytoplasmic fibrils, likely to be exported progeny RNA. These results provide new mechanistic insights into positive-strand RNA virus replication compartment structure, assembly, function and control.
正链RNA病毒是最大的病毒基因类别，包括许多重要病原体，如寨卡病毒。这些病毒在新型的、有膜包裹的微型细胞器中复制其RNA基因组，但这些区室中病毒蛋白和RNA的组织情况在很大程度上尚不清楚。我们利用冷冻电子断层扫描技术揭示了 flock house nodavirus（FHV）RNA复制区室许多以前未被认识的特征。这些线粒体外膜的球状内陷充满了电子致密的RNA纤维，其体积与RNA复制模板长度密切相关。每个小球的缩窄孔口由一个引人注目的杯状环结构覆盖，该结构包含多功能FHV RNA复制蛋白A。对这些环的亚断层平均显示出十二重对称性、同心侧翼突起和一个中央电子密度。许多环与长的细胞质纤维相关，可能是输出的子代RNA。这些结果为正链RNA病毒复制区室的结构、组装、功能和调控提供了新的机制见解。
