4bbk | pdb_00004bbk

Structural and functional characterisation of the kindlin-1 pleckstrin homology domain

spinqualitylabelsall models 4bbk, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4bbk is a 1 chain structure with sequence from Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: GOL Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed Inside-out activation of integrins is mediated via the binding of talin and kindlin to integrin beta-subunit cytoplasmic tails (CTs). The kindlin FERM domain is interrupted by a pleckstrin homology (PH) domain within its F2 subdomain. Here, we present data confirming the importance of the kindlin-1 PH domain for integrin activation, and its X-ray crystal structure at a resolution of 2.1 A revealing a C-terminal second alpha-helix integral to the domain but found only in the kindlin protein family. An isoform-specific salt-bridge occludes the canonical phosphoinositide binding site, but molecular dynamics (MD) simulations display transient switching to an alternative open conformer. Molecular docking reveals that the opening of the pocket would enable potential ligands to bind within it. Although lipid overlay assays suggested the PH domain binds inositol monophosphates, surface plasmon resonance (SPR) demonstrated weak affinities for Ins(3,4,5)P3 (KD ~100 muM) and no monophosphate binding. Removing the salt bridge by site-directed mutagenesis increases the PH domain affinity for Ins(3,4,5)P3 as measured by SPR, and enables it to bind PtdIns(3,5)P2 on a dot blot. Structural comparison with other PH domains suggests that the phosphate binding pocket in the kindlin-1 PH domain is more occluded than in kindlins -2 and -3 due to its salt bridge. In addition, the apparent affinity for Ins(3,4,5)P3 is affected by the presence of PO4 ions in the buffer. We suggest the physiological ligand of the kindlin-1 PH domain is most likely not an inositol phosphate but another phosphorylated species. Structural and functional characterisation of the kindlin-1 pleckstrin homology domain.,Yates LA, Lumb CN, Brahme NN, Zalyte R, Bird LE, De Colibus L, Owens RJ, Calderwood DA, Sansom MS, Gilbert RJ J Biol Chem. 2012 Nov 6. PMID:23132860 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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