405d
From Proteopedia
STRUCTURE OF A 16-MER RNA DUPLEX R(GCAGACUUAAAUCUGC)2 WITH WOBBLE LIKE A.C MISMATCHES
Overview
The crystal structure of a 16-mer, the longest known RNA duplex, has been determined at 2.5 A resolution. The hexadecamer r(GCAGACUUAAAUCUGC) contains isolated C.A/A.C mismatches with two hydrogen bonds. The two hydrogen bonds in the mismatches suggests that N1 of A is protonated even though the crystallization was done at neutral pH. Therefore, the C.A mismatch is a C.A+ wobble similar to the G.U wobble. The two C.A+ pairs are isolated by four Watson-Crick pairs and flanked by five Watson-Crick base-pairs on either sides. Kinks/bends of 20 degrees are observed at the wobble sites. The Watson-Crick base-pair A5.U26 on the 5'-side of the first C6.A27(+) wobble has a twist angle of 27 degrees compared to the 3'-side U7.A28 pair of 36 degrees. The twist angles are reversed (37 degrees and 26 degrees) in the second A11(+).C22 wobble because of the approximate dyad in the molecule, the flanking base-pair sequences are A.U pairs. The wobbles expand the major groove to 7.1 A/7.3 A. The duplexes form helical columns and are tightly packed around the 31-screw axis. The minor grooves of adjacent columns in juxtaposition interact through the O2' atoms and the anionic phosphate oxygen atoms.Copyright 1998 Academic Press.
About this Structure
Full crystallographic information is available from OCA.
Reference
Structure of a 16-mer RNA duplex r(GCAGACUUAAAUCUGC)2 with wobble C.A+ mismatches., Pan B, Mitra SN, Sundaralingam M, J Mol Biol. 1998 Nov 13;283(5):977-84. PMID:9799637 Page seeded by OCA on Sun May 4 22:16:12 2008
