1c4l
From Proteopedia
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SOLUTION STRUCTURE OF AN RNA DUPLEX INCLUDING A C-U BASE-PAIR
Overview
The formation of the C-U base pair in a duplex was observed in solution by means of the temperature profile of (15)N chemical shifts, and the precise geometry of the C-U base pair was also determined by NOE-based structure calculation. From the solution structure of the RNA oligomer, r[CGACUCAGG].r[CCUGCGUCG], it was found that a single C-U mismatch preferred being stacked in the duplex rather than being flipped-out even in solution. Moreover, it adopts an irregular geometry, where the amino nitrogen (N4) of the cytidine and keto-oxygen (O4) of the uridine are within hydrogen-bonding distance, as seen in crystals. To further prove the presence of a hydrogen bond in the C-U pair, we employed a point-labeled cytidine at the exocyclic amino nitrogen of the cytidine in the C-U pair. The temperature profile of its (15)N chemical shift showed a sigmoidal transition curve, indicating the presence of a hydrogen bond in the C-U pair in the duplex.
About this Structure
1C4L is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Solution structure of an RNA duplex including a C-U base pair., Tanaka Y, Kojima C, Yamazaki T, Kodama TS, Yasuno K, Miyashita S, Ono A, Ono A, Kainosho M, Kyogoku Y, Biochemistry. 2000 Jun 20;39(24):7074-80. PMID:10852704
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