Murray J, Buard J, Neil D L, Yeramian E, Tamaki K, Hollies C, Jeffreys A J
Department of Genetics, University of Leicester, Leicester LE1 7RH, UK.
Genome Res. 1999 Feb;9(2):130-6.
The highly variable human minisatellites MS32 (D1S8), MS31A (D7S21), and CEB1 (D2S90) all show recombination-based repeat instability restricted to the germline. Mutation usually results in polar interallelic conversion or occasionally in crossovers, which, at MS32 at least, extend into DNA flanking the repeat array, defining a localized recombination hotspot and suggesting that cis-acting elements in flanking DNA can influence repeat instability. Therefore, comparative sequence analysis was performed to search for common flanking elements associated with these unstable loci. All three minisatellites are located in GC-rich DNA abundant in dispersed and tandem repetitive elements. There were no significant sequence similarities between different loci upstream of the unstable end of the repeat array. Only one of the three loci showed clear evidence for putative coding sequences near the minisatellite. No consistent patterns of thermal stability or DNA secondary structure were shared by DNA flanking these loci. This work extends previous data on the genomic environment of minisatellites. In addition, this work suggests that recombinational activity is not controlled by primary or secondary characteristics of the DNA sequence flanking the repeat array and is not obviously associated with gene promoters as seen in yeast.
高度可变的人类小卫星MS32（D1S8）、MS31A（D7S21）和CEB1（D2S90）均表现出基于重组的重复序列不稳定性，且这种不稳定性仅限于生殖系。突变通常导致极性等位基因间转换，偶尔也会导致交叉互换，至少在MS32中，这种交叉互换会延伸到重复序列阵列侧翼的DNA中，从而定义了一个局部重组热点，并表明侧翼DNA中的顺式作用元件可影响重复序列的不稳定性。因此，进行了比较序列分析，以寻找与这些不稳定位点相关的共同侧翼元件。所有这三个小卫星均位于富含GC的DNA中，这些DNA中富含分散和串联重复元件。在重复序列阵列不稳定末端上游的不同位点之间没有明显的序列相似性。三个位点中只有一个在小卫星附近显示出存在推定编码序列的明确证据。这些位点侧翼的DNA没有共同的热稳定性或DNA二级结构模式。这项工作扩展了先前关于小卫星基因组环境的数据。此外，这项工作表明，重组活性不受重复序列阵列侧翼DNA序列的一级或二级特征控制，并且不像在酵母中那样明显与基因启动子相关。
