Crystal Structure of a Brominated RNA Helix with Four Mismatched Base Pairs: An Investigation into RNA Conformational Variability

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• 作者：Amy C. Anderson ; Robert H. O'Neil ; David J. Filman ; and Christin A. Frederick
• 刊名：Biochemistry
• 出版年：1999
• 出版时间：September 28, 1999
• 年：1999
• 卷：38
• 期：39
• 页码：12577 - 12585
• 全文大小：409K
• 年卷期：v.38,no.39(September 28, 1999)
• ISSN：1520-4995

文摘

The X-ray crystal structure of a brominated RNA helix with four mismatched base pairs andsequence r(UG^BrC^BrCAGUUCGCUGGC)₂ was determined to 2.1 Å using the methods of multiwavelengthanomalous diffraction (MAD) applied to the bromine K-absorption edge. There are three molecules inthe asymmetric unit with unique crystal-packing environments, revealing true conformational variabilityat high resolution for this sequence. The structure shows that the sequence itself does not define a consistentpattern of solvent molecules, with the exception of the mismatched base pairs, implying that specificRNA-protein interactions would occur only with the nucleotides. There are a number of significant tertiaryinteractions, some of which are a result of the brominated base pairs and others that are directly mediatedby the RNA 2' hydroxyl groups. The mismatched base pairs exhibit a solvent network as well as a stackingpattern with their nearest neighbors that validate previous thermodynamic analysis.