Utilizing the GAAA Tetraloop/Receptor To Facilitate Crystal Packing and Determination of the Structure of a CUG RNA Helix

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• 作者：Leslie A. Coonrod ; Jeremy R. Lohman ; J. Andrew Berglund
• 刊名：Biochemistry
• 出版年：2012
• 出版时间：October 23, 2012
• 年：2012
• 卷：51
• 期：42
• 页码：8330-8337
• 全文大小：597K
• 年卷期：v.51,no.42(October 23, 2012)
• ISSN：1520-4995

文摘

Myotonic dystrophy type 1 (DM1) is a microsatellite expansion disorder caused by the aberrant expansion of CTG repeats in the 3鈥?untranslated region of the DMPK gene. When transcribed, the toxic RNA CUG repeats sequester RNA binding proteins, which leads to disease symptoms. The expanded CUG repeats can adopt a double-stranded structure, and targeting this helix is a therapeutic strategy for DM1. To improve our understanding of the 5鈥睠UG/3鈥睪UC motif and how it may interact with proteins and small molecules, we designed a short CUG helix attached to a GAAA tetraloop/receptor to facilitate crystal packing. Here we report the highest-resolution structure (1.95 脜) to date of a GAAA tetraloop/receptor and the CUG helix it was used to crystallize. Within the CUG helix, we identify two different forms of noncanonical U-U pairs and reconfirm that CUG repeats are essentially A-form. An analysis of all noncanonical U-U pairs in the context of CUG repeats revealed six different classes of conformations that the noncanonical U-U pairs are able to adopt.