title: Microtubule associated protein tau binds to double-stranded but not single-stranded DNA.
abstract: Tau, a major microtubule-associated protein of the neuron, which is known to promote the assembly of and to stabilize microtubules, has also been seen associated with chromatin in neuronal cell lines, but its role in this subcellular compartment is still unknown. In this study, the binding of tau to DNA was investigated using the electrophoretic mobility shift assay. Using polynucleotide as probe, we found that tau bound to double-stranded but not to single-stranded DNA. Formation of tau-polynucleotide complex was disrupted by alkaline pH and a high concentration of NaCl, but was not affected by dithiothreitol. Electron microscopy revealed that the protein associated with the nucleic acid in a necklacelike manner. DNA-cellulose chromatography and radioimmunodot-blot analyses showed that calf thymus histones VI-S, VII-S and VIII-S could replace both recombinant human brain tau352 (tau-23) and tau441 (tau-40) from DNA. Thus, tau appears to bind to DNA reversibly in the presence of histones.
authors.affiliation: Laboratory of Visual Information Processing, Center for Brain and Cognitive Sciences, Institute of Biophysics, The Chinese Academy of Sciences, 15 Da Tun Rd, Chaoyang District, Beijing 100101, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Hua
authors.forename: R Q
authors.initials: RQ
authors.lastname: He
authors.forename: N
authors.initials: N
authors.lastname: Haque
authors.forename: M H
authors.initials: MH
authors.lastname: Qu
authors.forename: A
authors.initials: A
authors.lastname: del Carmen Alonso
authors.forename: I
authors.initials: I
authors.lastname: Grundke-Iqbal
authors.forename: K
authors.initials: K
authors.lastname: Iqbal
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D002846:Chromatography, Affinity; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000648:ultrastructure; D024202:Electrophoretic Mobility Shift Assay; D006657:Histones / Q000378:metabolism; D006801:Humans; D007526:Isoelectric Point; D007700:Kinetics; D009474:Neurons / Q000737:chemistry; D011863:Radioimmunoassay; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D016875:tau Proteins / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D006657:Histones; D011994:Recombinant Proteins; D016875:tau Proteins