Anomalous rapid electrophoretic mobility of DNA containing triplet repeats associated with human disease genes
Anomalous rapid electrophoretic mobility of DNA containing triplet repeats associated with human disease genes
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DOI：
10.1021/bi00049a027
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发表时间：
1995-12-12
期刊：
影响因子：
2.9
通讯作者：
Sinden, RR
中科院分区：
文献类型：
--
作者：
Chastain, PD;Eichler, EE;Sinden, RR
八种人类遗传性疾病与CTG或CGG三联体重复序列的扩增有关。扩张背后的分子病因学尚不清楚，但可能涉及复制，修复或重组中的不寻常DNA结构的参与。我们发现，含有CTG三联体重复来自人类强直性肌营养不良基因的DNA片段迁移速度比预期的非变性聚丙烯酰胺凝胶快20%，这表明存在一个不寻常的DNA螺旋结构内的CTG三联体重复。异常迁移与三倍体重复序列的数目、侧翼DNA的长度、聚丙烯酰胺的百分比和温度有关。放线菌素D的加入可降低这种效应。将爬行模型应用于电泳，结果与DNA的持续长度增加20%一致。PCR产物含有CTG或CGG重复脊髓小脑共济失调I型基因（SCA1）或脆性X FMR 1基因，分别也表现出较高的电泳迁移率。这些是第一个确定长度的序列，其迁移率的显著增加可归因于DNA中的序列依赖性结构元件。
Eight human genetic diseases have been associated with the expansion of CTG or CGG triplet repeats. The molecular etiology behind expansion is unknown but may involve participation of an unusual DNA structure in replication, repair, or recombination. We show that DNA fragments containing CTG triplet repeats derived from the human myotonic dystrophy gene migrate up to 20% faster than expected in nondenaturing polyacrylamide gels, suggesting the presence of an unusual DNA helix structure within the CTG triplet repeats. The anomalous migration is dependent upon the number of tripler repeats, the length of the flanking DNA, and the percentage and temperature of the polyacrylamide. The effect could be reduced by the addition of actinomycin D. Applying a reptation model for electrophoresis, the results are consistent with a 20% increase in persistence length of the DNA. PCR products containing CTG or CGG repeats from the spinocerebellar ataxia type I gene (SCA1) or the fragile X FMR1 gene, respectively, also showed higher electrophoretic mobility. These are the first sequences of defined length for which a dramatic increase in mobility can be attributed to sequence-dependent structural elements in DNA.