研究CTG和CCTG重复序列溶液结构的挑战

摘要/Abstract

摘要：

脱氧核糖核酸(DNA)重复序列的基因不稳定性和遗传神经退行性疾病有关. 通过在基因复制中形成异常结构，CTG和CCTG重复序列进行自我扩张，并会分别导致强直性肌营养不良类型1 (DM1) 和强直性肌营养不良类型2 (DM2). 尽管x-射线衍射晶体分析法在解决基因结构上是一个强大的技术，但是CTG和CCTG这些重复序列可能是因为其固有的灵活性，很难得到晶体，所以现在还没能成功鉴定其结构. 因此，核磁共振 (NMR) 光谱仍然是在单个脱氧核糖核酸层次上研究DNA结构的唯一技术. 最近，研究人员克服了包括由于重复系列导致的严重信号重叠、存在的多种构象及构象互换导致的光谱复杂性的挑战，顺利运用核磁共振技术研究了CTG和CCTG重复序列的结构. 通过适当的样品设计、样品操作技术、次序修改、及/或单个脱氧核糖核酸替代实验，利用¹H 和³¹P核磁共振波谱法确定了CTG和 CCTG 重复序列的结构特点. 该综述回顾详细阐述上述研究中所采用的技术.

关键词: 核磁共振(NMR), DNA结构, 强直性肌营养不良, CTG重复序列, CCTG重复序列

Abstract:

Genetic instability of deoxyribonucleic acid (DNA) repeating sequences has been found to associate with hereditary neurodegenerative diseases. It has been suggested that self-expansion of CTG and CCTG repeats would occur through the formation of unusual structures during DNA replication, leading to myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2), respectively. Although x-ray crystallography is a powerful technique in solving DNA structures, there has not been any successful structure determination of CTG or CCTG repeats probably due to the fact that the growth of diffraction-quality crystals has been hampered by the intrinsic flexibility of these repeating sequences. Therefore, nuclear magnetic resonance (NMR) spectroscopy remains to be the only technique that allows studying DNA structures at individual residue level. Recently, we have successfully overcome the challenges in NMR structural studies of CTG and CCTG repeats, including the severe signal overlap due to the repetitive nature of repeating sequences and the increase in spectral complexity owing to the presence of multiple conformers and conformational exchange. With appropriate sample design, sample handling technique, sequence modification and/or single-site substitution experiments, we have determined the structural features of CTG and CCTG repeats using ¹H and ³¹P NMR spectroscopy. This review provides an account of the strategies that have been applied in these studies.

Key words: NMR, DNA structures, myotonic dystrophy, CTG repeats, CCTG repeats

中图分类号:

O482.53

林锡乐. 研究CTG和CCTG重复序列溶液结构的挑战[J]. 波谱学杂志, 2012, 29(1): 1-20.

Sik Lok Lam. Overcoming the Challenges in Solution Structure Studies of CTG and CCTG Repeats[J]. Chinese Journal of Magnetic Resonance, 2012, 29(1): 1-20.

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