1eku
From Proteopedia
(New page: 200px<br /> <applet load="1eku" size="450" color="white" frame="true" align="right" spinBox="true" caption="1eku, resolution 2.9Å" /> '''CRYSTAL STRUCTURE OF...) |
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| - | [[Image:1eku.gif|left|200px]]<br /> | + | [[Image:1eku.gif|left|200px]]<br /><applet load="1eku" size="350" color="white" frame="true" align="right" spinBox="true" |
| - | <applet load="1eku" size=" | + | |
caption="1eku, resolution 2.9Å" /> | caption="1eku, resolution 2.9Å" /> | ||
'''CRYSTAL STRUCTURE OF A BIOLOGICALLY ACTIVE SINGLE CHAIN MUTANT OF HUMAN IFN-GAMMA'''<br /> | '''CRYSTAL STRUCTURE OF A BIOLOGICALLY ACTIVE SINGLE CHAIN MUTANT OF HUMAN IFN-GAMMA'''<br /> | ||
==Overview== | ==Overview== | ||
| - | A mutant form of human interferon-gamma (IFN-gamma SC1) that binds one | + | A mutant form of human interferon-gamma (IFN-gamma SC1) that binds one IFN-gamma receptor alpha chain (IFN-gamma R alpha) has been designed and characterized. IFN-gamma SC1 was derived by linking the two peptide chains of the IFN-gamma dimer by a seven-residue linker and changing His111 in the first chain to an aspartic acid residue. Isothermal titration calorimetry shows that IFN-gamma SC1 forms a 1:1 complex with its high-affinity receptor (IFN-gamma R alpha) with an affinity of 27(+/- 9) nM. The crystal structure of IFN-gamma SC1 has been determined at 2.9 A resolution from crystals grown in 1.4 M citrate solutions at pH 7.6. Comparison of the wild-type receptor-binding domain and the Asp111-containing domain of IFN-gamma SC1 show that they are structurally equivalent but have very different electrostatic surface potentials. As a result, surface charge rather than structural changes is likely responsible for the inability of the His111-->Asp domain of to bind IFN-gamma R alpha. The AB loops of IFN-gamma SC1 adopt conformations similar to the ordered loops of IFN-gamma observed in the crystal structure of the IFN-gamma/IFN-gamma R alpha complex. Thus, IFN-gamma R alpha binding does not result in a large conformational change in the AB loop as previously suggested. The structure also reveals the final six C-terminal amino acid residues of IFN-gamma SC1 (residues 253-258) that have not been observed in any other reported IFN-gamma structures. Despite binding to only one IFN-gamma R alpha, IFN-gamma SC1 is biologically active in cell proliferation, MHC class I induction, and anti-viral assays. This suggests that one domain of IFN-gamma is sufficient to recruit IFN-gamma R alpha and IFN-gamma R beta into a complex competent for eliciting biological activity. The current data are consistent with the main role of the IFN-gamma dimer being to decrease the dissociation constant of IFN-gamma for its cellular receptors. |
==Disease== | ==Disease== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1EKU 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:// | + | 1EKU 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=1EKU OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Curry, B.]] | [[Category: Curry, B.]] | ||
[[Category: DiGiacomo, R.]] | [[Category: DiGiacomo, R.]] | ||
| - | [[Category: Indelicato, S | + | [[Category: Indelicato, S R.]] |
[[Category: Landar, A.]] | [[Category: Landar, A.]] | ||
| - | [[Category: Parker, M | + | [[Category: Parker, M H.]] |
| - | [[Category: Walter, M | + | [[Category: Walter, M R.]] |
[[Category: SO4]] | [[Category: SO4]] | ||
[[Category: cytokine]] | [[Category: cytokine]] | ||
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[[Category: protein engineering]] | [[Category: protein engineering]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:28:50 2008'' |
Revision as of 10:28, 21 February 2008
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CRYSTAL STRUCTURE OF A BIOLOGICALLY ACTIVE SINGLE CHAIN MUTANT OF HUMAN IFN-GAMMA
Contents |
Overview
A mutant form of human interferon-gamma (IFN-gamma SC1) that binds one IFN-gamma receptor alpha chain (IFN-gamma R alpha) has been designed and characterized. IFN-gamma SC1 was derived by linking the two peptide chains of the IFN-gamma dimer by a seven-residue linker and changing His111 in the first chain to an aspartic acid residue. Isothermal titration calorimetry shows that IFN-gamma SC1 forms a 1:1 complex with its high-affinity receptor (IFN-gamma R alpha) with an affinity of 27(+/- 9) nM. The crystal structure of IFN-gamma SC1 has been determined at 2.9 A resolution from crystals grown in 1.4 M citrate solutions at pH 7.6. Comparison of the wild-type receptor-binding domain and the Asp111-containing domain of IFN-gamma SC1 show that they are structurally equivalent but have very different electrostatic surface potentials. As a result, surface charge rather than structural changes is likely responsible for the inability of the His111-->Asp domain of to bind IFN-gamma R alpha. The AB loops of IFN-gamma SC1 adopt conformations similar to the ordered loops of IFN-gamma observed in the crystal structure of the IFN-gamma/IFN-gamma R alpha complex. Thus, IFN-gamma R alpha binding does not result in a large conformational change in the AB loop as previously suggested. The structure also reveals the final six C-terminal amino acid residues of IFN-gamma SC1 (residues 253-258) that have not been observed in any other reported IFN-gamma structures. Despite binding to only one IFN-gamma R alpha, IFN-gamma SC1 is biologically active in cell proliferation, MHC class I induction, and anti-viral assays. This suggests that one domain of IFN-gamma is sufficient to recruit IFN-gamma R alpha and IFN-gamma R beta into a complex competent for eliciting biological activity. The current data are consistent with the main role of the IFN-gamma dimer being to decrease the dissociation constant of IFN-gamma for its cellular receptors.
Disease
Known diseases associated with this structure: AIDS, rapid progression to OMIM:[147570], Aplastic anemia OMIM:[147570], Hepatitis C virus, resistance to OMIM:[147570], Interferon, immune, deficiency OMIM:[147570], TSC2 angiomyolipomas, renal, modifier of OMIM:[147570], Tuberculosis, susceptibility to OMIM:[147570]
About this Structure
1EKU is a Single protein structure of sequence from Homo sapiens with as ligand. Full crystallographic information is available from OCA.
Reference
Design, characterization, and structure of a biologically active single-chain mutant of human IFN-gamma., Landar A, Curry B, Parker MH, DiGiacomo R, Indelicato SR, Nagabhushan TL, Rizzi G, Walter MR, J Mol Biol. 2000 May 26;299(1):169-79. PMID:10860730
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