Department of Microbial and Molecular Systems (M²S), Faculty of Bioscience Engineering, Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium.
FEMS Microbiol Rev. 2014 Jan;38(1):119-41. doi: 10.1111/1574-6976.12036. Epub 2013 Aug 28.
DNA tandem repeats (TRs), also designated as satellite DNA, are inter- or intragenic nucleotide sequences that are repeated two or more times in a head-to-tail manner. Because TR tracts are prone to strand-slippage replication and recombination events that cause the TR copy number to increase or decrease, loci containing TRs are hypermutable. An increasing number of examples illustrate that bacteria can exploit this instability of TRs to reversibly shut down or modulate the function of specific genes, allowing them to adapt to changing environments on short evolutionary time scales without an increased overall mutation rate. In this review, we discuss the prevalence and distribution of inter- and intragenic TRs in bacteria and the mechanisms of their instability. In addition, we review evidence demonstrating a role of TR variations in bacterial adaptation strategies, ranging from immune evasion and tissue tropism to the modulation of environmental stress tolerance. Nevertheless, while bioinformatic analysis reveals that most bacterial genomes contain a few up to several dozens of intra- and intergenic TRs, only a small fraction of these have been functionally studied to date.
DNA 串联重复（TRs），也称为卫星 DNA，是在基因内或基因间的核苷酸序列，以头到尾的方式重复两次或更多次。由于 TR 片段容易发生链滑动复制和重组事件，导致 TR 拷贝数增加或减少，因此含有 TR 的基因座具有高度突变性。越来越多的例子表明，细菌可以利用 TR 的这种不稳定性，可逆地关闭或调节特定基因的功能，使它们能够在短时间内适应不断变化的环境，而不会增加整体突变率。在这篇综述中，我们讨论了细菌中基因内和基因间 TR 的普遍性和分布，以及它们不稳定性的机制。此外，我们还回顾了证明 TR 变异在细菌适应策略中的作用的证据，这些策略范围从免疫逃避和组织嗜性到环境应激耐受性的调节。然而，尽管生物信息学分析表明大多数细菌基因组包含几个到几十个基因内和基因间的 TR，但迄今为止，只有一小部分 TR 得到了功能研究。
