1ozj
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(New page: 200px<br /> <applet load="1ozj" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ozj, resolution 2.4Å" /> '''Crystal structure of...)
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Revision as of 16:32, 12 November 2007
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Crystal structure of Smad3-MH1 bound to DNA at 2.4 A resolution
Overview
The Smad family of proteins mediates transforming growth factor-beta, signaling from cell membrane to the nucleus. In the nucleus, Smads serve, as transcription factors by directly binding to specific DNA sequences and, regulating the expression of ligand-response genes. A previous structural, analysis, at 2.8-A resolution, revealed a novel DNA-binding mode for the, Smad MH1 domain but did not allow accurate assignment of the fines, features of protein-DNA interactions. The crystal structure of a Smad3 MH1, domain bound to a palindromic DNA sequence, determined at 2.4-A, resolution, reveals a surprisingly important role for water molecules. The, asymmetric placement of the DNA-binding motif (a conserved 11-residue, beta-hairpin) in the major groove of DNA is buttressed by seven well, ordered water molecules. These water molecules make specific hydrogen, bonds to the DNA bases, the DNA phosphate backbones, and several critical, Smad3 residues. In addition, the MH1 domain is found to contain a bound, zinc atom using four invariant residues among Smad proteins, three, cysteines and one histidine. Removal of the zinc atom results in, compromised DNA binding activity. These results define the Smad MH1 domain, as a zinc-coordinating module that exhibits unique DNA binding properties.
About this Structure
1OZJ is a Single protein structure of sequence from Homo sapiens with ZN as ligand. Full crystallographic information is available from OCA.
Reference
Features of a Smad3 MH1-DNA complex. Roles of water and zinc in DNA binding., Chai J, Wu JW, Yan N, Massague J, Pavletich NP, Shi Y, J Biol Chem. 2003 May 30;278(22):20327-31. Epub 2003 Apr 9. PMID:12686552
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