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Structure paper

タイトル	In situ structures of the genome and genome-delivery apparatus in a single-stranded RNA virus.
ジャーナル・号・ページ	Nature, Vol. 541, Issue 7635, Page 112-116, Year 2017
掲載日	2017年1月5日
著者	Xinghong Dai / Zhihai Li / Mason Lai / Sara Shu / Yushen Du / Z Hong Zhou / Ren Sun /
PubMed 要旨	Packaging of the genome into a protein capsid and its subsequent delivery into a host cell are two fundamental processes in the life cycle of a virus. Unlike double-stranded DNA viruses, which pump ...Packaging of the genome into a protein capsid and its subsequent delivery into a host cell are two fundamental processes in the life cycle of a virus. Unlike double-stranded DNA viruses, which pump their genome into a preformed capsid, single-stranded RNA (ssRNA) viruses, such as bacteriophage MS2, co-assemble their capsid with the genome; however, the structural basis of this co-assembly is poorly understood. MS2 infects Escherichia coli via the host 'sex pilus' (F-pilus); it was the first fully sequenced organism and is a model system for studies of translational gene regulation, RNA-protein interactions, and RNA virus assembly. Its positive-sense ssRNA genome of 3,569 bases is enclosed in a capsid with one maturation protein monomer and 89 coat protein dimers arranged in a T = 3 icosahedral lattice. The maturation protein is responsible for attaching the virus to an F-pilus and delivering the viral genome into the host during infection, but how the genome is organized and delivered is not known. Here we describe the MS2 structure at 3.6 Å resolution, determined by electron-counting cryo-electron microscopy (cryoEM) and asymmetric reconstruction. We traced approximately 80% of the backbone of the viral genome, built atomic models for 16 RNA stem-loops, and identified three conserved motifs of RNA-coat protein interactions among 15 of these stem-loops with diverse sequences. The stem-loop at the 3' end of the genome interacts extensively with the maturation protein, which, with just a six-helix bundle and a six-stranded β-sheet, forms a genome-delivery apparatus and joins 89 coat protein dimers to form a capsid. This atomic description of genome-capsid interactions in a spherical ssRNA virus provides insight into genome delivery via the host sex pilus and mechanisms underlying ssRNA-capsid co-assembly, and inspires speculation about the links between nucleoprotein complexes and the origins of viruses.
リンク	Nature / PubMed:27992877 / PubMed Central
手法	EM (単粒子)
解像度	3.6 Å
構造データ	8397 5tc1 EMDB-8397, PDB-5tc1: In situ structures of the genome and genome-delivery apparatus in ssRNA bacteriophage MS2 手法: EM (単粒子) / 解像度: 3.6 Å
由来	enterobacteria phage ms2 (ファージ)
キーワード	viral protein/rna (ウイルス性) / asymmetric cryoEM reconstruction / ssRNA genome structure / genome-delivery apparatus / genome-capsid interactions / viral protein-rna complex (ウイルス性)