1bym
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SOLUTION STRUCTURES OF THE C-TERMINAL DOMAIN OF DIPHTHERIA TOXIN REPRESSOR
OverviewOverview
The diphtheria toxin repressor (DtxR) is the best-characterized member of, a family of homologous proteins that regulate iron uptake and virulence, gene expression in the Gram-positive bacteria. DtxR contains two domains, that are separated by a short, unstructured linker. The N-terminal domain, is structurally well-defined and is responsible for Fe2+ binding, dimerization, and DNA binding. The C-terminal domain adopts a fold similar, to eukaryotic Src homology 3 domains, but the functional role of the, C-terminal domain in repressor activity is unknown. The solution structure, of the C-terminal domain, consisting of residues N130-L226 plus a, 13-residue N-terminal extension, has been determined by using NMR, spectroscopy. Residues before A147 are highly mobile and adopt a random, coil conformation, but residues A147-L226 form a single structured domain, consisting of five beta-strands and three helices arranged into a, partially orthogonal, two-sheet beta-barrel, similar to the structure, observed in the crystalline Co2+ complex of full-length DtxR. Chemical, shift perturbation studies demonstrate that a proline-rich peptide, corresponding to residues R125-G139 of intact DtxR binds to the C-terminal, domain in a pocket formed by residues in beta-strands 2, 3, and 5, and, helix 3. Binding of the proline-rich peptide by the C-terminal domain of, DtxR presents an example of peptide binding by a prokaryotic Src homology, 3-like protein. The results of this study, combined with previous x-ray, studies of intact DtxR, provide insights into a possible biological, function of the C-terminal domain in regulating repressor activity.
About this StructureAbout this Structure
1BYM is a Single protein structure of sequence from Corynebacterium diphtheriae. Full crystallographic information is available from OCA.
ReferenceReference
Solution structure and peptide binding studies of the C-terminal src homology 3-like domain of the diphtheria toxin repressor protein., Wang G, Wylie GP, Twigg PD, Caspar DL, Murphy JR, Logan TM, Proc Natl Acad Sci U S A. 1999 May 25;96(11):6119-24. PMID:10339551
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