2awq
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(New page: 200px<br /><applet load="2awq" size="350" color="white" frame="true" align="right" spinBox="true" caption="2awq" /> '''Solution Structure of pseudouridine-32 modif...)
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Revision as of 16:11, 29 January 2008
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Solution Structure of pseudouridine-32 modified anticodon stem-loop of E. coli tRNAPhe
Overview
Nucleoside base modifications can alter the structures and dynamics of RNA, molecules and are important in tRNAs for maintaining translational, fidelity and efficiency. The unmodified anticodon stem-loop from, Escherichia coli tRNA(Phe) forms a trinucleotide loop in solution, but, Mg2+ and dimethylallyl modification of A37 N6 destabilize the, loop-proximal base pairs and increase the mobility of the loop, nucleotides. The anticodon arm has three additional modifications, psi32, psi39, and A37 C2-thiomethyl. We have used NMR spectroscopy to investigate, the structural and dynamical effects of psi32 on the anticodon stem-loop, from E.coli tRNA(Phe). The psi32 modification does not significantly alter, the structure of the anticodon stem-loop relative to the unmodified parent, molecule. The stem of the RNA molecule includes base pairs psi32-A38 and, U33-A37 and the base of psi32 stacks between U33 and A31. The glycosidic, bond of psi32 is in the anti configuration and is paired with A38 in a, Watson-Crick geometry, unlike residue 32 in most crystal structures of, tRNA. The psi32 modification increases the melting temperature of the stem, by approximately 3.5 degrees C, although the psi32 and U33 imino, resonances are exchange broadened. The results suggest that psi32, functions to preserve the stem integrity in the presence of additional, loop modifications or after reorganization of the loop into a, translationally functional conformation.
About this Structure
2AWQ is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Solution structure of psi32-modified anticodon stem-loop of Escherichia coli tRNAPhe., Cabello-Villegas J, Nikonowicz EP, Nucleic Acids Res. 2005 Dec 23;33(22):6961-71. Print 2005. PMID:16377777
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