1ik5

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spinqualitylabelsall models 1ik5, resolution 1.8Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal Structure of a 14mer RNA Containing Double UU Bulges in Two Crystal Forms: A Novel U*(AU) Intramolecular Base Triple

Overview

The RNA/DNA 14-mer, (gguauuucgguaCc)2 with consecutive uridine bulges, (underlined) on each strand has been determined in two crystal forms, spermine bound (Sp-form) and spermine free (Sp-free). The former was, solved by the MAD method with three-wavelength data collected at, Brookhaven National Laboratory (BNL); the later isomorphous structure was, solved by the molecular replacement method using data collected on our, Raxis IIc imaging plate system. The two crystal forms belong to the space, group C2 with one molecule of double-stranded 14 mer in the asymmetric, unit. The Sp-form has cell constants, a = 60.06, b = 29.10, c = 52.57 A, beta = 120.79 degrees and was refined to 1.7 A resolution with a final, Rwork/Rfree of 19.8%/22.7% using 8,549 independent reflections. The, Sp-free structure has cell constants, a = 60.06, b = 29.58, c = 52.50 A, beta = 120.85 degrees and was refined to 1.8 A with a final Rwork/ Rfree, of 20.8%/23.2% using 6,285 unique reflections. The two structures are, identical, except that the Sp-form has a spermine bound in the major, groove, parallel to the RNA helical axis. One of the uridine bulges forms, a novel intramolecular U*(A x U) base triple. The helices are in the, C3'-endo conformation (A-form), but the bulges adopt the C2'-endo sugar, pucker. Furthermore, the bulges induce a kink (30 degrees) in the helix, axis and a very large twist (55 degrees) between the base pairs flanking, the bulges. The Sp-form has one Mg2+ ion whereas the Sp-free form has two, Mg2+ ions.

About this Structure

1IK5 is a Protein complex structure of sequences from [1] with MG as ligand. Full crystallographic information is available from OCA.

Reference

Crystal structures of two forms of a 14-mer RNA/DNA chimer duplex with double UU bulges: a novel intramolecular U*(A x U) base triple., Deng J, Xiong Y, Sudarsanakumar C, Shi K, Sundaralingam M, RNA. 2001 Oct;7(10):1425-31. PMID:11680847

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