1f5t

DIPHTHERIA TOX REPRESSOR (C102D MUTANT) COMPLEXED WITH NICKEL AND DTXR CONSENSUS BINDING SEQUENCE

spinqualitylabelsall models 1f5t, resolution 3.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1f5t is a 6 chain structure with sequence from Corynebacterium diphtheriae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: NI Resources: FirstGlance, OCA, RCSB, PDBsum Function [DTXR_CORDI] Iron-binding repressor of the dipheteria toxin gene expression. May serve as a global regulator of gene expression. Represses ripA under iron excess. 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 expression of diphtheria toxin is controlled by the diphtheria toxin repressor (DtxR). Under conditions of high iron concentration, DtxR binds the tox operator to inhibit transcription. To study how DNA binding specificity is achieved by this repressor, we solved the crystal structure of the nickel(II) activated DtxR(C102D) mutant complexed with a 43mer DNA duplex containing the DtxR consensus binding sequence. Structural analysis of this complex and comparison with a previously determined DtxR(C102D)-Ni(II)-tox operator ternary complex revealed unusual van der Waals interactions between Ser37/Pro39 of the repressor helix-turn-helix (HTH) motif and the methyl groups of specific thymine bases in the consensus binding sequence. Gel mobility shift assays utilizing deoxyuridine modified duplex DNA probes proved the importance of these interactions: the four methyl groups shown to interact with Ser37/Pro39 in the crystal structure contribute a total of 3.4 kcal/mol to binding energy. Thus, in addition to making base-specific hydrogen-bonding interactions to the DNA through its Gln43 residue, DtxR also recognizes methyl groups at certain positions in the DNA sequence with its Ser37 and Pro39 side chains, to achieve binding specificity toward its cognate operator sequences. Methyl groups of thymine bases are important for nucleic acid recognition by DtxR.,Chen CS, White A, Love J, Murphy JR, Ringe D Biochemistry. 2000 Aug 29;39(34):10397-407. PMID:10956029 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Diphtheria toxin repressor

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