Department of Biology, Emory University, Atlanta, GA 30322, USA.
Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
Int J Mol Sci. 2021 Apr 21;22(9):4309. doi: 10.3390/ijms22094309.
Satellite DNA consists of abundant tandem repeats that play important roles in cellular processes, including chromosome segregation, genome organization and chromosome end protection. Most satellite DNA repeat units are either of nucleosomal length or 5-10 bp long and occupy centromeric, pericentromeric or telomeric regions. Due to high repetitiveness, satellite DNA sequences have largely been absent from genome assemblies. Although few conserved satellite-specific sequence motifs have been identified, DNA curvature, dyad symmetries and inverted repeats are features of various satellite DNAs in several organisms. Satellite DNA sequences are either embedded in highly compact gene-poor heterochromatin or specialized chromatin that is distinct from euchromatin. Nevertheless, some satellite DNAs are transcribed into non-coding RNAs that may play important roles in satellite DNA function. Intriguingly, satellite DNAs are among the most rapidly evolving genomic elements, such that a large fraction is species-specific in most organisms. Here we describe the different classes of satellite DNA sequences, their satellite-specific chromatin features, and how these features may contribute to satellite DNA biology and evolution. We also discuss how the evolution of functional satellite DNA classes may contribute to speciation in plants and animals.
卫星 DNA 由大量串联重复组成，在细胞过程中发挥重要作用，包括染色体分离、基因组组织和染色体末端保护。大多数卫星 DNA 重复单元要么是核小体长度，要么是 5-10bp 长，占据着着丝粒、着丝粒周围或端粒区域。由于高度重复，卫星 DNA 序列在基因组组装中大部分缺失。尽管已经确定了少数保守的卫星特异性序列基序，但在几种生物体中，DNA 曲率、二联体对称性和反向重复是各种卫星 DNA 的特征。卫星 DNA 序列要么嵌入高度紧凑的基因贫瘠异染色质中，要么嵌入与常染色质不同的特殊染色质中。然而，一些卫星 DNA 被转录为非编码 RNA，这些 RNA 可能在卫星 DNA 功能中发挥重要作用。有趣的是，卫星 DNA 是基因组中进化最快的元素之一，在大多数生物体中，很大一部分是物种特异性的。在这里，我们描述了不同类别的卫星 DNA 序列、它们的卫星特异性染色质特征，以及这些特征如何有助于卫星 DNA 的生物学和进化。我们还讨论了功能卫星 DNA 类别的进化如何有助于动植物的物种形成。
