2fhz
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(New page: 200px<br /><applet load="2fhz" size="450" color="white" frame="true" align="right" spinBox="true" caption="2fhz, resolution 1.15Å" /> '''Molecular Basis of I...)
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Revision as of 08:26, 21 November 2007
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Molecular Basis of Inhibition of the Ribonuclease Activity in Colicin E5 by Its Cognate Immunity Protein
Overview
Colicin E5 is a tRNA-specific ribonuclease that recognizes and cleaves, four tRNAs in Escherichia coli that contain the hypermodified nucleoside, queuosine (Q) at the wobble position. Cells that produce colicin E5 also, synthesize the cognate immunity protein (Im5) that rapidly and tightly, associates with colicin E5 to prevent it from cleaving its own tRNAs to, avoid suicide. We report here the crystal structure of Im5 in a complex, with the activity domain of colicin E5 (E5-CRD) at 1.15A resolution. The, structure reveals an extruded domain from Im5 that docks into the recessed, RNA binding cleft in E5-CRD, resulting in extensive interactions between, the two proteins. The interactions are primarily hydrophilic, with an, interface that contains complementary surface charges between the two, proteins. Detailed interactions in three separate regions of the interface, account for specific recognition of colicin E5 by Im5. Furthermore, single-site mutational studies of Im5 confirmed the important role of, particular residues in recognition and binding of colicin E5. Structural, comparison of the complex reported here with E5-CRD alone, as well as with, a docking model of RNA-E5-CRD, indicates that Im5 achieves its inhibition, by physically blocking the cleft in colicin E5 that engages the RNA, substrate.
About this Structure
2FHZ is a Protein complex structure of sequences from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Molecular basis of inhibition of the ribonuclease activity in colicin E5 by its cognate immunity protein., Luna-Chavez C, Lin YL, Huang RH, J Mol Biol. 2006 Apr 28;358(2):571-9. Epub 2006 Feb 24. PMID:16524591
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