Moldovan M A
Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, 127051 Russia.
Department of Bioengineering and Bioinformatics, Moscow State University, Moscow, 119991 Russia.
Mol Biol (Mosk). 2019 Mar-Apr;53(2):218-224. doi: 10.1134/S0026898419020125.
Bacterial chromosomes are widely thought of as circular DNA molecules. However, linear bacterial chromosomes, as well as linear mitochondrial and plastid chromosomes, are fairly common. The most frequent causes of linearization are reparation system defects, incorporation of plasmids in the genome, and recombination compromising the circular topology of chromosomes. Genomes of some bacterial species had undergone frequent linearization-circularization events, which resulted in an increased variability of gene content at linear chromosome ends. Similarly to eukaryotes, bacteria that have linear genomes face the problem of end replication, which different species solve in a variety of ways. A theoretically important issue is the adaptive value of chromosome linearization. This review discusses theories concerning the evolution of linear genomes and supporting experiments. The most common mechanisms of linear bacterial genomes replication and possible ways of their emergence are also considered.
细菌染色体通常被认为是环状DNA分子。然而，线性细菌染色体以及线性线粒体和质体染色体相当常见。线性化的最常见原因是修复系统缺陷、质粒整合到基因组中以及重组破坏了染色体的环状拓扑结构。一些细菌物种的基因组经历了频繁的线性化-环化事件，这导致线性染色体末端基因含量的变异性增加。与真核生物类似，具有线性基因组的细菌面临着末端复制的问题，不同物种以多种方式解决这个问题。一个理论上重要的问题是染色体线性化的适应性价值。本综述讨论了关于线性基因组进化的理论及支持实验。还考虑了线性细菌基因组复制的最常见机制及其出现的可能方式。
