Photoclickable dendritic molecular glue: noncovalent-to-covalent photochemical transformation of protein hybrids.

Noriyuki Uchida, Kou Okuro, Yamato Niitani, Xiao Ling, Takayuki Ariga, Michio Tomishige, Takuzo Aida

Index: J. Am. Chem. Soc. 135(12) , 4684-7, (2013)

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Abstract

A water-soluble dendron with a fluorescein isothiocyanate (FITC) fluorescent label and bearing nine pendant guanidinium ion (Gu(+))/benzophenone (BP) pairs at its periphery (Glue(BP)-FITC) serves as a "photoclickable molecular glue". By multivalent salt-bridge formation between Gu(+) ions and oxyanions, Glue(BP)-FITC temporarily adheres to a kinesin/microtubule hybrid. Upon subsequent exposure to UV light, this noncovalent binding is made permanent via a cross-linking reaction mediated by carbon radicals derived from the photoexcited BP units. This temporal-to-permanent transformation by light occurs quickly and efficiently in this preorganized state, allowing the movements of microtubules on a kinesin-coated glass plate to be photochemically controlled. A fundamental difference between such temporal and permanent bindings was visualized by the use of "optical tweezers".