1bwn
From Proteopedia
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==Overview== | ==Overview== | ||
| - | BACKGROUND: The activity of Bruton's tyrosine kinase (Btk) is important, for the maturation of B cells. A variety of point mutations in this enzyme, result in a severe human immunodeficiency known as X-linked, agammaglobulinemia (XLA). Btk contains a pleckstrin-homology (PH) domain, that specifically binds phosphatidylinositol 3,4,5-trisphosphate and, hence, responds to signalling via phosphatidylinositol 3-kinase. Point, mutations in the PH domain might abolish membrane binding, preventing, signalling via Btk. RESULTS: We have determined the crystal structures of, the wild-type PH domain and a gain-of-function mutant E41K in complex with, D-myo-inositol 1,3,4,5-tetra-kisphosphate (Ins (1,3,4,5)P4). The inositol, Ins (1,3,4,5)P4 binds to a site that is similar to the inositol, ... | + | BACKGROUND: The activity of Bruton's tyrosine kinase (Btk) is important, for the maturation of B cells. A variety of point mutations in this enzyme, result in a severe human immunodeficiency known as X-linked, agammaglobulinemia (XLA). Btk contains a pleckstrin-homology (PH) domain, that specifically binds phosphatidylinositol 3,4,5-trisphosphate and, hence, responds to signalling via phosphatidylinositol 3-kinase. Point, mutations in the PH domain might abolish membrane binding, preventing, signalling via Btk. RESULTS: We have determined the crystal structures of, the wild-type PH domain and a gain-of-function mutant E41K in complex with, D-myo-inositol 1,3,4,5-tetra-kisphosphate (Ins (1,3,4,5)P4). The inositol, Ins (1,3,4,5)P4 binds to a site that is similar to the inositol, 1,4,5-trisphosphate binding site in the PH domain of phospholipase, C-delta. A second Ins (1,3,4,5)P4 molecule is associated with the domain, of the E41K mutant, suggesting a mechanism for its constitutive, interaction with membrane. The affinities of Ins (1,3,4,5)P4 to the wild, type (Kd = 40 nM), and several XLA-causing mutants have been measured, using isothermal titration calorimetry. CONCLUSIONS: Our data provide an, explanation for the specificity and high affinity of the interaction with, phosphatidylinositol 3,4,5-trisphosphate and lead to a classification of, the XLA mutations that reside in the Btk PH domain. Mis-sense mutations, that do not simply destabilize the PH fold either directly affect the, interaction with the phosphates of the lipid head group or change, electrostatic properties of the lipid-binding site. One point mutation, (Q127H) cannot be explained by these facts, suggesting that the PH domain, of Btk carries an additional function such as interaction with a Galpha, protein. |
==About this Structure== | ==About this Structure== | ||
| - | 1BWN is a | + | 1BWN 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 ZN and 4IP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Transferred_entry:_2.7.10.1_and_2.7.10.2 Transferred entry: 2.7.10.1 and 2.7.10.2], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.1.112 2.7.1.112] Structure known Active Sites: ZN1 and ZN2. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1BWN OCA]. |
==Reference== | ==Reference== | ||
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[[Category: zinc binding]] | [[Category: zinc binding]] | ||
| - | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 12:59:28 2007'' |
Revision as of 10:54, 5 November 2007
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PH DOMAIN AND BTK MOTIF FROM BRUTON'S TYROSINE KINASE MUTANT E41K IN COMPLEX WITH INS(1,3,4,5)P4
Overview
BACKGROUND: The activity of Bruton's tyrosine kinase (Btk) is important, for the maturation of B cells. A variety of point mutations in this enzyme, result in a severe human immunodeficiency known as X-linked, agammaglobulinemia (XLA). Btk contains a pleckstrin-homology (PH) domain, that specifically binds phosphatidylinositol 3,4,5-trisphosphate and, hence, responds to signalling via phosphatidylinositol 3-kinase. Point, mutations in the PH domain might abolish membrane binding, preventing, signalling via Btk. RESULTS: We have determined the crystal structures of, the wild-type PH domain and a gain-of-function mutant E41K in complex with, D-myo-inositol 1,3,4,5-tetra-kisphosphate (Ins (1,3,4,5)P4). The inositol, Ins (1,3,4,5)P4 binds to a site that is similar to the inositol, 1,4,5-trisphosphate binding site in the PH domain of phospholipase, C-delta. A second Ins (1,3,4,5)P4 molecule is associated with the domain, of the E41K mutant, suggesting a mechanism for its constitutive, interaction with membrane. The affinities of Ins (1,3,4,5)P4 to the wild, type (Kd = 40 nM), and several XLA-causing mutants have been measured, using isothermal titration calorimetry. CONCLUSIONS: Our data provide an, explanation for the specificity and high affinity of the interaction with, phosphatidylinositol 3,4,5-trisphosphate and lead to a classification of, the XLA mutations that reside in the Btk PH domain. Mis-sense mutations, that do not simply destabilize the PH fold either directly affect the, interaction with the phosphates of the lipid head group or change, electrostatic properties of the lipid-binding site. One point mutation, (Q127H) cannot be explained by these facts, suggesting that the PH domain, of Btk carries an additional function such as interaction with a Galpha, protein.
About this Structure
1BWN is a Single protein structure of sequence from Homo sapiens with ZN and 4IP as ligands. Active as Transferred entry: 2.7.10.1 and 2.7.10.2, with EC number 2.7.1.112 Structure known Active Sites: ZN1 and ZN2. Full crystallographic information is available from OCA.
Reference
Structure of the PH domain from Bruton's tyrosine kinase in complex with inositol 1,3,4,5-tetrakisphosphate., Baraldi E, Carugo KD, Hyvonen M, Surdo PL, Riley AM, Potter BV, O'Brien R, Ladbury JE, Saraste M, Structure. 1999 Apr 15;7(4):449-60. PMID:10196129
Page seeded by OCA on Mon Nov 5 12:59:28 2007
Categories: Homo sapiens | Single protein | Transferred entry: 2.7.10.1 and 2.7.10.2 | Baraldi, E. | Carugo, K.Djinovic. | Hyvoenen, M. | Potter, B. | Riley, A. | Saraste, M. | Surdo, P.Lo. | 4IP | ZN | 3 | 4 | 5)-tetrakisphosphate | Btk motif | Inositol-(1 | Ph domain | Transferase | Tyrosine-protein kinase | X-linked agammaglobulinemia | Zinc binding
