López-Bueno Alberto, Gil-Ranedo Jon, Almendral José M
Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) and Department of Molecular Biology, Universidad Autónoma de Madrid, Madrid, Spain.
Faculty of Health: Medicine, Dentistry and Human Sciences, University of Plymouth, Plymouth, UK.
Subcell Biochem. 2024;105:403-430. doi: 10.1007/978-3-031-65187-8_11.
Icosahedral viruses exhibit elegant pathways of capsid assembly and maturation regulated by symmetry principles. Assembly is a dynamic process driven by consecutive and genetically programmed morphogenetic interactions between protein subunits. The non-symmetric capsid subunits are gathered by non-covalent contacts and interactions in assembly intermediates, which serve as blocks to build a symmetric capsid. In some virus examples, the assembly of the protein shell further requires non-symmetric interactions among intermediates to fold into specific conformations. In this chapter, the morphogenesis of some small and structurally simple icosahedral viruses, including representative members of the parvoviruses, picornaviruses, and polyomaviruses as paradigms, is described in some detail. Despite their small size, the assembly of these icosahedral viruses may follow rather complex pathways, as they may occur in different subcellular compartments, involve a panoply of cellular and viral factors, and regulatory protein post-translational modifications that challenge its comprehensive understanding. Mechanisms of viral genome encapsidation may imply direct interactions between the genome and the assembly intermediates, or active packaging into a preformed empty capsid. Further, membranes and factors at specific subcellular compartments may also be critically required for virus maturation. The high stability of intermediates and the process of viral maturation contribute to the overall irreversible character of the assembly process. These and other small, structurally less complex icosahedral viruses were pioneer models to understand basic principles of virus assembly, continue to be leading subjects of morphogenetic analyses, and have inspired ongoing studies on the assembly of larger, structurally more complex viruses as well as cellular and synthetic macromolecular complexes.
二十面体病毒展现出由对称原理调控的衣壳组装和成熟的精妙途径。组装是一个动态过程，由蛋白质亚基之间连续且受基因编程的形态发生相互作用驱动。非对称的衣壳亚基通过非共价接触和组装中间体中的相互作用聚集在一起，这些中间体作为构建对称衣壳的模块。在一些病毒实例中，蛋白质外壳的组装还需要中间体之间的非对称相互作用以折叠成特定构象。在本章中，将详细描述一些小型且结构简单的二十面体病毒的形态发生，包括细小病毒、微小核糖核酸病毒和多瘤病毒的代表性成员作为范例。尽管它们体积小，但这些二十面体病毒的组装可能遵循相当复杂的途径，因为它们可能发生在不同的亚细胞区室，涉及大量细胞和病毒因子，以及具有挑战性的蛋白质翻译后修饰，从而难以全面理解。病毒基因组包装机制可能意味着基因组与组装中间体之间的直接相互作用，或者主动包装进预先形成的空衣壳。此外，特定亚细胞区室的膜和因子对于病毒成熟也可能至关重要。中间体的高稳定性和病毒成熟过程促成了组装过程整体的不可逆特性。这些以及其他小型、结构较不复杂的二十面体病毒是理解病毒组装基本原理的先驱模型，仍然是形态发生分析的主要研究对象，并激发了对更大、结构更复杂的病毒以及细胞和合成大分子复合物组装的持续研究。
