Structure of an RNA Internal Loop Consisting of Tandem C-A+ Base Pairs,
- 1 August 1998
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 37 (34) , 11726-11731
- https://doi.org/10.1021/bi980758j
Abstract
The crystal structure of the RNA octamer 5‘-CGC(CA)GCG-3‘ has been determined from X-ray diffraction data to 2.3 Å resolution. In the crystal, this oligomer forms a self-complementary double helix in the asymmetric unit. Tandem non-Watson−Crick C-A and A-C base pairs comprise an internal loop in the middle of the duplex, which is incorporated with little distortion of the A-form double helix. From the geometry of the C-A base pairs, it is inferred that the adenosine imino group is protonated and donates a hydrogen bond to the carbonyl group of the cytosine. The wobble geometry of the C-A+ base pairs is very similar to that of the common U-G non-Watson−Crick pair.Keywords
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