Actin binding of ezrin is activated by specific recognition of PIP2-functionalized lipid bilayers

作者：Janke Matthias; Herrig Alexander; Austermann Judith; Gerke Volker; Steinem Claudia; Janshoff Andreas^*

来源：Biochemistry, 2008, 47(12): 3762-3769.

DOI：10.1021/bi702542s

In a quantitative manner, we investigated the mechanism of switching ezrin from the dormant to the active, F-actin binding state by recognition of PIP2. For this purpose, we established a novel in vitro model mimicking ezrin-mediated membrane-cytoskeleton attachment and compared the F-actin binding capability of ezrin that either had been coupled via a His tag to a lipid bilayer displaying Ni-NTA or had been bound to supported membranes containing PIP2. Epifluorescence and colloidal probe microscopy (CPM) were employed to demonstrate ezrin's conformational switch into an active conformation capable of binding F-actin. Epifluorescence images revealed attachment of fluorescently labeled F-actin solely to PIP2-bound ezrin. For the first time, colloidal spheres equipped with an artificial cytoskeleton composed of firmly attached F-actin filaments were used to measure quantitatively the maximal adhesion forces and the work of adhesion of the ezrin-F-actin interface. We found that the work of adhesion between PIP2-bound ezrin and F-actin is substantially larger than that measured between F-actin and ezrin bound to the membrane via the His tag. Collectively, these data indicate that activation of ezrin can occur as a consequence of PIP2 binding and does not require additional cofactors.

• 出版日期2008-3-25
• 单位河北医科大学