综述阅读: 原核基因组中的短序列 DNA 重复

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期刊

Microbiology and molecular biology reviews（13.044/Q1）

Short-Sequence DNA Repeats in Prokaryotic Genomes （1998）

原核基因组中的短序列 DNA 重复

INTRODUCTION

Repetitive DNA, which occurs in large quantities in eukaryotic cells, has been increasingly identified in prokaryotes. In eukaryotic genomes, this repetitive DNA is infrequently associated with coding regions and consequently is located primarily in extragenic regions. Repetitive DNA consists of simple homopolymeric tracts of a single nucleotide type [poly(A), poly(G), poly(T), or poly(C)] or of large or small numbers of several multimeric classes of repeats. These multimeric repeats are built from identical units (homogeneous repeats), mixed units (heterogeneous repeats), or degenerate repeat sequence motifs (Fig. 1 shows a schematic overview). Short tandemly repeated sequences occur in several to thousands of copies dispersed through the genome of many if not all higher eukaryotes. These sequence elements showed hypervariability among individual persons, and genetic mapping can be used to prepare DNA fingerprints that are specific for an individual. Although these sequences were initially defined as mini- and microsatellite DNA consisting of short sequence repeats (SSRs) or short tandem repeats (STRs), Nakamura et al. introduced a more accurate terminology. Some of the repeats, especially those representing a single locus and showing inter-individual length variability, were designated “variable number of tandem repeat” (VNTR) loci. VNTRs and SSRs are now well-established molecular targets forpedigree analysis. For the sake of clarity, we will use the abbreviation SSR as the acronym for most of the DNA repeats found in prokaryotes. This is analogous to eukaryotic nomenclature. However, some of the repeats could also be classified as genuine VNTRs in the sense that repeat number variation is associated with a single genetic locus.

大量存在于真核细胞中的重复 DNA 已在原核生物中越来越多地被发现。在真核基因组中，这种重复的 DNA 很少与编码区相关，因此主要位于基因外区域。重复 DNA 由单一核苷酸类型 [poly(A)、poly(G)、poly(T) 或 poly(C)] 的简单均聚物束或大量或少量的几个多聚体类别的重复组成。这些多聚体重复由相同单元（同质重复）、混合单元（异质重复）或简并重复序列基序构成（图 1 显示示意图）。短串联重复序列以数到数千个拷贝出现，分散在许多（如果不是全部）高等真核生物的基因组中。这些序列元素在个体之间表现出高度变异性，基因图谱可用于制备个体特有的 DNA 指纹。尽管这些序列最初被定义为由短序列重复 (SSR) 或短串联重复 (STR) 组成的微型和微卫星 DNA，但 Nakamura 等人。引入了更准确的术语。一些重复，特别是那些代表单个基因座并显示个体间长度可变性的重复，被指定为“可变数量的串联重复”（VNTR）基因座。 VNTRs 和 SSRs 现在是谱系分析的成熟分子靶标。为了清楚起见，我们将使用缩写 SSR 作为原核生物中发现的大多数 DNA 重复的首字母缩写词。这类似于真核生物命名法。然而，在重复数变异与单个基因位点相关的意义上，一些重复也可以归类为真正的VNTR。rnia Los Angeles. b The two sequence motifs were found to be adjacent; both motifs occurred five times and were exactly neighboring.

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