2k29

Structure of the DBD domain of E. coli antitoxin RelB

spinqualitylabelsall models 2k29 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2k29 is a 2 chain structure with sequence from Escherichia coli. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Solution NMR Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RELB_ECOLI Antitoxin component of a toxin-antitoxin (TA) module. Counteracts the effect of RelE via direct protein-protein interaction, enabling the reversion of translation inhibition. Also acts as an autorepressor of relBE transcription. DNA-binding and repression is stronger when complexed with corepressor RelE. Increased transcription rate of relBE and activation of relE is consistent with a lower level of RelB in starved cells due to degradation of RelB by protease Lon. Seems to be a principal mediator of cell death in liquid media. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The Escherichia coli chromosomal relBE operon encodes a toxin-antitoxin system, which is autoregulated by its protein products, RelB and RelE. RelB acts as a transcriptional repressor and RelE functions as a cofactor to enhance the repressor activity of RelB. Here, we present the NMR-derived structure of a RelB dimer and show that a RelB dimer recognizes a hexad repeat in the palindromic operator region through a ribbon-helix-helix motif. Our biochemical data show that two weakly associated RelB dimers bind to the adjacent repeats in the 3'-site of the operator (O(R)) at a moderate affinity (K(d), approximately 10(-5) M). However, in the presence of RelE, a RelB tetramer binds two distinct binding sites within the operator region, each with an enhanced affinity (K(d), approximately 10(-6) M for the low-affinity site, O(L), and 10(-8) M for the high-affinity site, O(R)). We propose that the enhanced affinity for the operator element is mediated by a cooperative DNA binding by a pair of RelB dimers and that the interaction between RelB dimers is strongly augmented by the presence of the cognate toxin RelE. Structural mechanism of transcriptional autorepression of the Escherichia coli RelB/RelE antitoxin/toxin module.,Li GY, Zhang Y, Inouye M, Ikura M J Mol Biol. 2008 Jun 27;380(1):107-19. Epub 2008 Apr 22. PMID:18501926 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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