1cdu: Difference between revisions
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'''STRUCTURE OF T-CELL SURFACE GLYCOPROTEIN CD4 MUTANT WITH PHE 43 REPLACED BY VAL''' | {{Structure | ||
|PDB= 1cdu |SIZE=350|CAPTION= <scene name='initialview01'>1cdu</scene>, resolution 2.7Å | |||
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'''STRUCTURE OF T-CELL SURFACE GLYCOPROTEIN CD4 MUTANT WITH PHE 43 REPLACED BY VAL''' | |||
==Overview== | ==Overview== | ||
The T-cell antigen coreceptor CD4 also serves as the receptor for the envelope glycoprotein gp120 of HIV. Extensive mutational analysis of CD4 has implicated residues from a portion of the extracellular amino-terminal domain (D1) in gp120 binding. However, none of these proteins has been fully characterized biophysically, and thus the precise effects on molecular structure and binding interactions are unknown. In the present study, we produced soluble versions of three mutant CD4 molecules (F43V, G47S, and A55F) and characterized their structural properties, thermostability, and ability to bind gp120. Crystallographic and thermodynamic analysis showed minimal structural alterations in the F43V and G47S mutant proteins, which have solvent-exposed mutant side chains. In contrast, some degree of disorder appears to exist in the folded state of A55F, as a result of mutating a buried side chain. Real time kinetic measurements of the interaction of the mutant proteins with gp120 showed affinity decreases of 5-fold for G47S, 50-fold for A55F, and 200-fold for F43V. Although both rate constants for the binding reaction were affected by these mutations, the loss in affinity was mainly due to a decrease in on rates, with less drastic changes occurring in the off rates. These observations suggest the involvement of conformational adaptation in the CD4-gp120 interaction. Together, the structural and kinetic data confirm that F43V is a critical residue in gp120 recognition site, which may also include main chain interactions at residue Gly-47. | The T-cell antigen coreceptor CD4 also serves as the receptor for the envelope glycoprotein gp120 of HIV. Extensive mutational analysis of CD4 has implicated residues from a portion of the extracellular amino-terminal domain (D1) in gp120 binding. However, none of these proteins has been fully characterized biophysically, and thus the precise effects on molecular structure and binding interactions are unknown. In the present study, we produced soluble versions of three mutant CD4 molecules (F43V, G47S, and A55F) and characterized their structural properties, thermostability, and ability to bind gp120. Crystallographic and thermodynamic analysis showed minimal structural alterations in the F43V and G47S mutant proteins, which have solvent-exposed mutant side chains. In contrast, some degree of disorder appears to exist in the folded state of A55F, as a result of mutating a buried side chain. Real time kinetic measurements of the interaction of the mutant proteins with gp120 showed affinity decreases of 5-fold for G47S, 50-fold for A55F, and 200-fold for F43V. Although both rate constants for the binding reaction were affected by these mutations, the loss in affinity was mainly due to a decrease in on rates, with less drastic changes occurring in the off rates. These observations suggest the involvement of conformational adaptation in the CD4-gp120 interaction. Together, the structural and kinetic data confirm that F43V is a critical residue in gp120 recognition site, which may also include main chain interactions at residue Gly-47. | ||
==About this Structure== | ==About this Structure== | ||
1CDU is a [ | 1CDU is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CDU OCA]. | ||
==Reference== | ==Reference== | ||
Kinetic and structural analysis of mutant CD4 receptors that are defective in HIV gp120 binding., Wu H, Myszka DG, Tendian SW, Brouillette CG, Sweet RW, Chaiken IM, Hendrickson WA, Proc Natl Acad Sci U S A. 1996 Dec 24;93(26):15030-5. PMID:[http:// | Kinetic and structural analysis of mutant CD4 receptors that are defective in HIV gp120 binding., Wu H, Myszka DG, Tendian SW, Brouillette CG, Sweet RW, Chaiken IM, Hendrickson WA, Proc Natl Acad Sci U S A. 1996 Dec 24;93(26):15030-5. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/8986758 8986758] | ||
[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
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[[Category: transmembrane]] | [[Category: transmembrane]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 10:23:06 2008'' | ||
Revision as of 11:23, 20 March 2008
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STRUCTURE OF T-CELL SURFACE GLYCOPROTEIN CD4 MUTANT WITH PHE 43 REPLACED BY VAL
OverviewOverview
The T-cell antigen coreceptor CD4 also serves as the receptor for the envelope glycoprotein gp120 of HIV. Extensive mutational analysis of CD4 has implicated residues from a portion of the extracellular amino-terminal domain (D1) in gp120 binding. However, none of these proteins has been fully characterized biophysically, and thus the precise effects on molecular structure and binding interactions are unknown. In the present study, we produced soluble versions of three mutant CD4 molecules (F43V, G47S, and A55F) and characterized their structural properties, thermostability, and ability to bind gp120. Crystallographic and thermodynamic analysis showed minimal structural alterations in the F43V and G47S mutant proteins, which have solvent-exposed mutant side chains. In contrast, some degree of disorder appears to exist in the folded state of A55F, as a result of mutating a buried side chain. Real time kinetic measurements of the interaction of the mutant proteins with gp120 showed affinity decreases of 5-fold for G47S, 50-fold for A55F, and 200-fold for F43V. Although both rate constants for the binding reaction were affected by these mutations, the loss in affinity was mainly due to a decrease in on rates, with less drastic changes occurring in the off rates. These observations suggest the involvement of conformational adaptation in the CD4-gp120 interaction. Together, the structural and kinetic data confirm that F43V is a critical residue in gp120 recognition site, which may also include main chain interactions at residue Gly-47.
About this StructureAbout this Structure
1CDU is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
Kinetic and structural analysis of mutant CD4 receptors that are defective in HIV gp120 binding., Wu H, Myszka DG, Tendian SW, Brouillette CG, Sweet RW, Chaiken IM, Hendrickson WA, Proc Natl Acad Sci U S A. 1996 Dec 24;93(26):15030-5. PMID:8986758
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