Open Conformation of Ezrin Bound to Phosphatidylinositol 4,5-Bisphosphate and to F-actin Revealed by Neutron Scattering*
| Autor: | Flora Meilleur, Jeong Ho Ju, Dazhi Liu, David J.E. Callaway, Jinkui Zhao, Lilin He, Zimei Bu, Jayant James Jayasundar |
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| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: |
Models
Molecular Phosphatidylinositol 4 5-Diphosphate Sodium-Hydrogen Exchangers Moesin Cooperativity Plasma protein binding macromolecular substances Biochemistry environment and public health Ezrin X-Ray Diffraction Radixin Scattering Small Angle Humans Cytoskeleton Protein Structure Quaternary Molecular Biology Chemistry Cortical actin cytoskeleton Cell Biology Surface Plasmon Resonance Actin cytoskeleton Phosphoproteins Actins Cell biology Protein Structure Tertiary Cytoskeletal Proteins Kinetics Neutron Diffraction Amino Acid Substitution Protein Structure and Folding Mutagenesis Site-Directed lipids (amino acids peptides and proteins) Protein Binding |
| Popis: | Ezrin is a member of the ezrin-radixin-moesin family (ERM) of adapter proteins that are localized at the interface between the cell membrane and the cortical actin cytoskeleton, and they regulate a variety of cellular functions. The structure representing a dormant and closed conformation of an ERM protein has previously been determined by x-ray crystallography. Here, using contrast variation small angle neutron scattering, we reveal the structural changes of the full-length ezrin upon binding to the signaling lipid phosphatidylinositol 4,5-bisphosphate (PIP(2)) and to F-actin. Ezrin binding to F-actin requires the simultaneous binding of ezrin to PIP(2). Once bound to F-actin, the opened ezrin forms more extensive contacts with F-actin than generally depicted, suggesting a possible role of ezrin in regulating the interfacial structure and dynamics between the cell membrane and the underlying actin cytoskeleton. In addition, using gel filtration, we find that the conformational opening of ezrin in response to PIP(2) binding is cooperative, but the cooperativity is disrupted by a phospho-mimic mutation S249D in the 4.1-ezrin/radixin/moesin (FERM) domain of ezrin. Using surface plasmon resonance, we show that the S249D mutation weakens the binding affinity and changes the kinetics of 4.1-ERM to PIP(2) binding. The study provides the first structural view of the activated ezrin bound to PIP(2) and to F-actin. |
| Databáze: | OpenAIRE |
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