Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Science for Life Laboratory, Umeå University, Umeå, Sweden.
Exp Suppl. 2022;114:1-42. doi: 10.1007/978-3-030-93306-7_1.
Microsporidia represent an evolutionary outlier in the tree of life and occupy the extreme edge of the eukaryotic domain with some of their biological features. Many of these unicellular fungi-like organisms have reduced their genomic content to potentially the lowest limit. With some of the most compacted eukaryotic genomes, microsporidia are excellent model organisms to study reductive evolution and its functional consequences. While the growing number of sequenced microsporidian genomes have elucidated genome composition and organization, a recent increase in complementary post-genomic studies has started to shed light on the impacts of genome reduction in these unique pathogens. This chapter will discuss the biological framework enabling genome minimization and will use one of the most ancient and essential macromolecular complexes, the ribosome, to illustrate the effects of extreme genome reduction on a structural, molecular, and cellular level. We outline how reductive evolution in microsporidia has shaped DNA organization, the composition and function of the ribosome, and the complexity of the ribosome biogenesis process. Studying compacted mechanisms, processes, or macromolecular machines in microsporidia illuminates their unique lifestyle and provides valuable insights for comparative eukaryotic structural biology.
微孢子虫在生命之树上代表一个进化的异常分支，占据真核域的极端边缘，具有一些独特的生物学特征。许多这些单细胞真菌样生物已经将其基因组内容减少到潜在的最低限度。由于具有一些最紧凑的真核生物基因组，微孢子虫是研究简化进化及其功能后果的优秀模式生物。随着越来越多的微孢子虫基因组测序阐明了基因组组成和组织，最近增加的补充后基因组研究开始揭示基因组简化对这些独特病原体的影响。本章将讨论使基因组最小化的生物学框架，并将使用最古老和最基本的大分子复合物之一核糖体，来说明极端基因组简化对结构、分子和细胞水平的影响。我们概述了微孢子虫中的简化进化如何塑造 DNA 组织、核糖体的组成和功能以及核糖体生物发生过程的复杂性。研究微孢子虫中压缩的机制、过程或大分子机器揭示了它们独特的生活方式，并为比较真核结构生物学提供了有价值的见解。
