Tau protein binds single‐stranded DNA sequence specifically – the proof obtained in vitro with non‐equilibrium capillary electrophoresis of equilibrium mixtures

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Abstract
Tau is a microtubule-associated protein, which plays an important role in physiology and pathology of neurons. Tau has been recently reported to bind double-stranded DNA (dsDNA) but not to bind single-stranded DNA (ssDNA) [Cell. Mol. Life Sci. 2003, 60, 413-421]. Here, we prove that tau binds not only dsDNA but also ssDNA. This finding was facilitated by using two kinetic capillary electrophoresis methods: (i) non-equilibrium capillary electrophoresis of equilibrium mixtures (NECEEM); (ii) affinity-mediated NECEEM. Using the new approach, we observed, for the first time, that tau could induce dissociation of strands in dsDNA by binding one of them in a sequence-specific fashion. Moreover, we determined the equilibrium dissociation constants for all tau-DNA complexes studied.