Olson A J, Bricogne G, Harrison S C
J Mol Biol. 1983 Nov 25;171(1):61-93. doi: 10.1016/s0022-2836(83)80314-3.
The structure of tomato bushy stunt virus has been determined crystallographically to 2.9 A resolution. Details are presented of both the molecular structure and the methods by which it has been solved. The icosahedrally symmetric viral shell is composed of 180 protein subunits (Mr 43,000), with three similar but distinct modes of subunit bonding. This capacity for alternative packing is due to localized flexibility in the folded polypeptide (hinges between domains) and to multiple conformations for surface side-chains. The polypeptide backbone has an essentially invariant fold within a compact domain. A mechanism for correct positioning of the different modes of subunit interaction is evident from the structure of the TBSV particle. Thirty-five residues of the polypeptide chain fold in an ordered way on 60 of the 180 subunits, forming an internal framework. Interaction of folded domains with this framework permits accuracy of long-range geometry (correct curvature and closure) to be determined by unambiguous switching between alternative local contact angles. RNA packs tightly into the particle interior. Protein-RNA interactions occur through parts of the subunit that are flexibly linked to the well-ordered domains of the shell. This variable interaction imposes minimum restrictions on the folding of the RNA chain.
番茄丛矮病毒的结构已通过晶体学方法确定,分辨率达到2.9埃。本文介绍了其分子结构以及解析该结构所采用的方法的详细信息。具有二十面体对称性的病毒外壳由180个蛋白质亚基(分子量43,000)组成,亚基结合存在三种相似但不同的模式。这种交替堆积的能力归因于折叠多肽中的局部灵活性(结构域之间的铰链区)以及表面侧链的多种构象。多肽主链在紧密的结构域内具有基本不变的折叠方式。从番茄丛矮病毒颗粒的结构中可以明显看出一种不同亚基相互作用模式正确定位的机制。多肽链的35个残基在180个亚基中的60个上以有序方式折叠,形成一个内部框架。折叠结构域与该框架的相互作用使得通过在不同局部接触角之间明确切换来确定远程几何形状的准确性(正确的曲率和封闭性)成为可能。RNA紧密堆积在颗粒内部。蛋白质 - RNA相互作用通过亚基中与外壳有序结构域灵活连接的部分发生。这种可变的相互作用对RNA链的折叠施加了最小限制。