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Updated: Aug 30, 2026

Iterative Optimization of DNA Duplexes for Crystallization of SeqA-DNA Complexes
Published on: November 1, 2012
Crystal structure of a bulged RNA tetraplex at 1.1 a resolution: implications for a novel binding site in RNA
Baocheng Pan1, Yong Xiong, Ke Shi
1Department of Chemistry and Biochemistry, The Ohio State University, 200 Johnston Lab, 176 West 19th Avenue, Columbus, OH, USA.
Abstract:
Bulges are an important structural motif in RNA and can be used as recognition and interaction sites in RNA-protein interaction and RNA-RNA interaction. Here we report the first crystal structure of a bulged RNA tetraplex at 1.1 A resolution. The hexamer r(U)(BrdG)r(UGGU) forms a parallel tetraplex with the uridine sandwiched by guanines bulging out. The bulged uridine adopts the syn glycosidic conformation and its O2 and N3 atoms face outwards, serving as an effective recognition and interaction site. The bulge formation both widens the groove width and changes the groove hydrogen-bonding pattern on its 5' side. However, the bulge does not make any bends or kinks in the tetraplex structure. The present study demonstrates the dramatic difference between uridine and guanine in forming tetraplex structure. In addition, both G(syn) tetrad and G(anti) tetrad have been observed. They display the same base-pairing pattern and similar C1'-C1' distance but different hydrogen-bonding patterns in the groove.
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