Binding of moesin and ezrin to membranes containing phosphatidylinositol (4,5) bisphosphate: A comparative study of the affinity constants and conformational changes

Ofelia Maniti (1) , Nada Khalifat (2) , Kriti Goggia (1) , Fabien Dalonneau (1) , Christophe Guérin (3) , Laurent Blanchoin (3) , Laurence Ramos (2) , Catherine Picart (1)

1 LMGP - Laboratoire des matériaux et du génie physique
2 L2C - Laboratoire Charles Coulomb
3 LPCV - Laboratoire de physiologie cellulaire végétale

The plasma membrane-cytoskeleton interface is a dynamic structure participating in a variety of cellular events. Moesin and ezrin, proteins from the ezrin/radixin/moesin (ERM) family, provide a direct linkage between the cytoskeleton and the membrane via their interaction with phosphatidylinositol 4,5-bisphosphate (PIP2). PIP2 binding is considered as a prerequisite step in ERM activation. The main objective of this work was to compare moesin and ezrin interaction with PIP2-containing membranes in terms of affinity and to analyze secondary structure modifications leading eventually to ERM activation. For this purpose, we used two types of biomimetic model membranes, large and giant unilamellar vesicles. The dissociation constant between moesin and PIP2-containing large unilamellar vesicles or PIP2-containing giant unilamellar vesicles was found to be very similar to that between ezrin and PIP2-containing large unilamellar vesicles or PIP2- containing giant unilamellar vesicles. In addition, both proteins were found to undergo conformational changes after binding to PIP2-containing large unilamellar vesicles. Changes were evidenced by an increased sensitivity to proteolysis, modifications in the fluorescence intensity of the probe attached to the C-terminus and in the proportion of secondary structure elements.

Mots clés: ERM protein; Vesicles; Fluorescence spectroscopy; Infrared spectroscopy; TRANSFORM INFRARED-SPECTROSCOPY; RADIXIN FERM DOMAIN; F-ACTIN BINDING; UNILAMELLAR VESICLES; ERM PROTEINS; LINKER EZRIN; ACTIVATION; CYTOSKELETON; EZRIN/RADIXIN/MOESIN

Mots clés: Phosphoinositide; Membrane-protein interaction; CELL CORTEX

Domaines: Biophysique [physics.bio-ph]; Biologie cellulaire

Ofelia Maniti, Nada Khalifat, Kriti Goggia, Fabien Dalonneau, Christophe Guérin, et al.. Binding of moesin and ezrin to membranes containing phosphatidylinositol (4,5) bisphosphate: A comparative study of the affinity constants and conformational changes. Biochimica et Biophysica Acta:Biomembranes, 2012, 1818 (11), pp.2839. ⟨10.1016/j.bbamem.2012.07.004⟩. ⟨hal-00730777⟩