2dfx
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(New page: 200px<br /><applet load="2dfx" size="450" color="white" frame="true" align="right" spinBox="true" caption="2dfx, resolution 1.9Å" /> '''Crystal structure of ...)
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Revision as of 07:28, 21 November 2007
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Crystal structure of the carboxy terminal domain of colicin E5 complexed with its inhibitor
Overview
Colicin E5--a tRNase toxin--specifically cleaves QUN (Q: queuosine), anticodons of the Escherichia coli tRNAs for Tyr, His, Asn and Asp. Here, we report the crystal structure of the C-terminal ribonuclease domain, (CRD) of E5 complexed with a substrate analog, namely, dGpdUp, at a, resolution of 1.9 A. Thisstructure is the first to reveal the substrate, recognition mechanism of sequence-specific ribonucleases. E5-CRD realized, the strict recognition for both the guanine and uracil bases of dGpdUp, forming Watson-Crick-type hydrogen bonds and ring stacking interactions, thus mimicking the codons of mRNAs to bind to tRNA anticodons. The docking, model of E5-CRD with tRNA also suggests its substrate preference for tRNA, over ssRNA. In addition, the structure of E5-CRD/dGpdUp along with the, mutational analysis suggests that Arg33 may play an important role in the, catalytic activity, and Lys25/Lys60 may also be involved without His in, E5-CRD. Finally, the comparison of the structures of E5-CRD/dGpdUp and, E5-CRD/ImmE5 (an inhibitor protein) complexes suggests that the binding, mode of E5-CRD and ImmE5 mimics that of mRNA and tRNA; this may represent, the evolutionary pathway of these proteins from the RNA-RNA interaction, through the RNA-protein interaction of tRNA/E5-CRD.
About this Structure
2DFX is a Protein complex structure of sequences from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Structural basis for sequence-dependent recognition of colicin E5 tRNase by mimicking the mRNA-tRNA interaction., Yajima S, Inoue S, Ogawa T, Nonaka T, Ohsawa K, Masaki H, Nucleic Acids Res. 2006;34(21):6074-82. Epub 2006 Nov 11. PMID:17099236
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