1dd1
From Proteopedia
(New page: 200px<br /> <applet load="1dd1" size="450" color="white" frame="true" align="right" spinBox="true" caption="1dd1, resolution 2.62Å" /> '''CRYSTAL STRUCTURE A...) |
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| - | [[Image:1dd1.gif|left|200px]]<br /> | + | [[Image:1dd1.gif|left|200px]]<br /><applet load="1dd1" size="350" color="white" frame="true" align="right" spinBox="true" |
| - | <applet load="1dd1" size=" | + | |
caption="1dd1, resolution 2.62Å" /> | caption="1dd1, resolution 2.62Å" /> | ||
'''CRYSTAL STRUCTURE ANALYSIS OF THE SMAD4 ACTIVE FRAGMENT'''<br /> | '''CRYSTAL STRUCTURE ANALYSIS OF THE SMAD4 ACTIVE FRAGMENT'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Smad4 functions as a common mediator of transforming growth | + | BACKGROUND: Smad4 functions as a common mediator of transforming growth factor beta (TGF-beta) signaling by forming complexes with the phosphorylated state of pathway-restricted SMAD proteins that act in specific signaling pathways to activate transcription. SMAD proteins comprise two domains, the MH1 and MH2 domain, separated by a linker region. The transcriptional activity and synergistic effect of Smad4 require a stretch of proline-rich sequence, the SMAD-activation domain (SAD), located N-terminal of the MH2 domain. To understand how the SAD contributes to Smad4 function, the crystal structure of a fragment including the SAD and MH2 domain (S4AF) was determined. RESULTS: The structure of the S4AF trimer reveals novel features important for Smad4 function. A Smad4-specific sequence insertion within the MH2 domain interacts with the C-terminal tail to form a structural extension from the core. This extension (the TOWER) contains a solvent-accessible glutamine-rich helix. The SAD reinforces the TOWER and the structural core through interactions; two residues involved in these interactions are targets of tumorigenic mutation. The solvent-accessible proline residues of the SAD are located on the same face as the glutamine-rich helix of the TOWER, forming a potential transcription activation surface. A tandem sulfate-ion-binding site was identified within the subunit interface, which may interact with the phosphorylated C-terminal sequence of pathway-restricted SMAD proteins. CONCLUSIONS: The structure suggests that the SAD provides transcriptional capability by reinforcing the structural core and coordinating with the TOWER to present the proline-rich and glutamine-rich surfaces for interaction with transcription partners. The sulfate-ion-binding sites are potential 'receptors' for the phosphorylated sequence of pathway-restricted SMAD proteins in forming a heteromeric complex. The structure thus provides a new model that can be tested using biochemical and cellular approaches. |
==Disease== | ==Disease== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1DD1 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with SO4 as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1DD1 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DD1 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Lam, S | + | [[Category: Lam, S W.]] |
[[Category: Lin, K.]] | [[Category: Lin, K.]] | ||
| - | [[Category: Qin, B | + | [[Category: Qin, B Y.]] |
[[Category: SO4]] | [[Category: SO4]] | ||
[[Category: b-sheet sandwich helix-turn-helix]] | [[Category: b-sheet sandwich helix-turn-helix]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:15:22 2008'' |
Revision as of 10:15, 21 February 2008
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CRYSTAL STRUCTURE ANALYSIS OF THE SMAD4 ACTIVE FRAGMENT
Contents |
Overview
BACKGROUND: Smad4 functions as a common mediator of transforming growth factor beta (TGF-beta) signaling by forming complexes with the phosphorylated state of pathway-restricted SMAD proteins that act in specific signaling pathways to activate transcription. SMAD proteins comprise two domains, the MH1 and MH2 domain, separated by a linker region. The transcriptional activity and synergistic effect of Smad4 require a stretch of proline-rich sequence, the SMAD-activation domain (SAD), located N-terminal of the MH2 domain. To understand how the SAD contributes to Smad4 function, the crystal structure of a fragment including the SAD and MH2 domain (S4AF) was determined. RESULTS: The structure of the S4AF trimer reveals novel features important for Smad4 function. A Smad4-specific sequence insertion within the MH2 domain interacts with the C-terminal tail to form a structural extension from the core. This extension (the TOWER) contains a solvent-accessible glutamine-rich helix. The SAD reinforces the TOWER and the structural core through interactions; two residues involved in these interactions are targets of tumorigenic mutation. The solvent-accessible proline residues of the SAD are located on the same face as the glutamine-rich helix of the TOWER, forming a potential transcription activation surface. A tandem sulfate-ion-binding site was identified within the subunit interface, which may interact with the phosphorylated C-terminal sequence of pathway-restricted SMAD proteins. CONCLUSIONS: The structure suggests that the SAD provides transcriptional capability by reinforcing the structural core and coordinating with the TOWER to present the proline-rich and glutamine-rich surfaces for interaction with transcription partners. The sulfate-ion-binding sites are potential 'receptors' for the phosphorylated sequence of pathway-restricted SMAD proteins in forming a heteromeric complex. The structure thus provides a new model that can be tested using biochemical and cellular approaches.
Disease
Known diseases associated with this structure: Juvenile polyposis/hereditary hemorrhagic telangiectasia syndrome OMIM:[600993], Pancreatic cancer OMIM:[600993], Polyposis, juvenile intestinal OMIM:[600993]
About this Structure
1DD1 is a Single protein structure of sequence from Homo sapiens with as ligand. Full crystallographic information is available from OCA.
Reference
Crystal structure of a transcriptionally active Smad4 fragment., Qin B, Lam SS, Lin K, Structure. 1999 Dec 15;7(12):1493-503. PMID:10647180
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