3i9q
Crystal Structure of the triple mutant S19G-P20D-R21S of alpha spectrin SH3 domain
Structural highlights
FunctionSPTN1_CHICK Morphologically, spectrin-like proteins appear to be related to spectrin, showing a flexible rod-like structure. They can bind actin but seem to differ in their calmodulin-binding activity. In nonerythroid tissues, spectrins, in association with some other proteins, may play an important role in membrane organization. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedalpha-Spectrin SH3-domain (Spc-SH3) crystallization is characterized by very fast growth of the crystals in the presence of ammonium sulfate as a precipitant agent. The origin of this behaviour can be attributed to the presence of a proline residue that participates in a crystal contact mimicking the binding of proline-rich sequences to SH3 domains. This residue, Pro20, is located in the RT loop and is the main contact in one of the interfaces present in the orthorhombic Spc-SH3 crystal structures. In order to understand the molecular interactions that are responsible for the very fast crystal growth of the wild-type (WT) Spc-SH3 crystals, the crystal structure of a triple mutant in which the residues Ser19-Pro20-Arg21 in the RT loop have been replaced by Gly19-Asp20-Ser21 (GDS Spc-SH3 mutant) has been solved. The removal of the critical proline residue results in slower nucleation of the Spc-SH3 crystals and a different arrangement of the protein molecules in the unit cell, leading to a crystal that belongs to the tetragonal space group P4(1)2(1)2, with unit-cell parameters a = b = 42.231, c = 93.655 A, and that diffracts to 1.45 A resolution. For both WT Spc-SH3 and the GDS mutant, light-scattering experiments showed that a dimer was formed in solution within a few minutes of the addition of 2 M ammonium sulfate at pH 6.5 and allowed the proposal of a mechanism for the nucleation and crystal growth of Spc-SH3 in which the Pro20 residue plays a key role in the rate of crystal growth. The effect of a proline residue on the rate of growth and the space group of alpha-spectrin SH3-domain crystals.,Camara-Artigas A, Andujar-Sanchez M, Ortiz-Salmeron E, Cuadri C, Casares S Acta Crystallogr D Biol Crystallogr. 2009 Dec;65(Pt 12):1247-52. Epub 2009, Nov 17. PMID:19966410[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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