title: Oligomerization of the microtubule-associated protein tau is mediated by its N-terminal sequences: implications for normal and pathological tau action.
abstract: Despite extensive structure-function analyses, the molecular mechanisms of normal and pathological tau action remain poorly understood. How does the C-terminal microtubule-binding region regulate microtubule dynamics and bundling? In what biophysical form does tau transfer trans-synaptically from one neuron to another, promoting neurodegeneration and dementia? Previous biochemical/biophysical work led to the hypothesis that tau can dimerize via electrostatic interactions between two N-terminal 'projection domains' aligned in an anti-parallel fashion, generating a multivalent complex capable of interacting with multiple tubulin subunits. We sought to test this dimerization model directly. Native gel analyses of full-length tau and deletion constructs demonstrate that the N-terminal region leads to multiple bands, consistent with oligomerization. Ferguson analyses of native gels indicate that an N-terminal fragment (tau(45-230) ) assembles into heptamers/octamers. Ferguson analyses of denaturing gels demonstrates that tau(45-230) can dimerize even in sodium dodecyl sulfate. Atomic force microscopy reveals multiple levels of oligomerization by both full-length tau and tau(45-230) . Finally, ion mobility-mass spectrometric analyses of tau(106-144) , a small peptide containing the core of the hypothesized dimerization region, also demonstrate oligomerization. Thus, multiple independent strategies demonstrate that the N-terminal region of tau can mediate higher order oligomerization, which may have important implications for both normal and pathological tau action. The microtubule-associated protein tau is essential for neuronal development and maintenance, but is also central to Alzheimer's and related dementias. Unfortunately, the molecular mechanisms underlying normal and pathological tau action remain poorly understood. Here, we demonstrate that tau can homo-oligomerize, providing novel mechanistic models for normal tau action (promoting microtubule growth and bundling, suppressing microtubule shortening) and pathological tau action (poisoning of oligomeric complexes).
authors.affiliation: Neuroscience Research Institute, University of California, Santa Barbara, California, USA.|Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA.
authors.forename: H Eric
authors.initials: HE
authors.lastname: Feinstein
authors.affiliation: Neuroscience Research Institute, University of California, Santa Barbara, California, USA.|Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Benbow
authors.affiliation: Neuroscience Research Institute, University of California, Santa Barbara, California, USA.
authors.forename: Nichole E
authors.initials: NE
authors.lastname: LaPointe
authors.affiliation: Department of Bioengineering, Department of Mechanical Engineering and Materials Science Graduate Program, University of California, San Diego, California, USA.
authors.forename: Nirav
authors.initials: N
authors.lastname: Patel
authors.affiliation: Department of Bioengineering, Department of Mechanical Engineering and Materials Science Graduate Program, University of California, San Diego, California, USA.
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Ramachandran
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, USA.
authors.forename: Thanh D
authors.initials: TD
authors.lastname: Do
authors.affiliation: Neuroscience Research Institute, University of California, Santa Barbara, California, USA.|Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA.
authors.forename: Michelle R
authors.initials: MR
authors.lastname: Gaylord
authors.affiliation: Neuroscience Research Institute, University of California, Santa Barbara, California, USA.|Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA.
authors.forename: Noelle E
authors.initials: NE
authors.lastname: Huskey
authors.affiliation: Department of Chemistry, Westmont College, Santa Barbara, California, USA.
authors.forename: Nicolette
authors.initials: N
authors.lastname: Dressler
authors.affiliation: Department of Chemistry, Westmont College, Santa Barbara, California, USA.
authors.forename: Megan
authors.initials: M
authors.lastname: Korff
authors.affiliation: Department of Chemistry, Westmont College, Santa Barbara, California, USA.
authors.forename: Brady
authors.initials: B
authors.lastname: Quon
authors.affiliation: Department of Chemistry, Westmont College, Santa Barbara, California, USA.
authors.forename: Kristi Lazar
authors.initials: KL
authors.lastname: Cantrell
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Bowers
authors.affiliation: Department of Bioengineering, Department of Mechanical Engineering and Materials Science Graduate Program, University of California, San Diego, California, USA.
authors.forename: Ratnesh
authors.initials: R
authors.lastname: Lal
authors.affiliation: Neuroscience Research Institute, University of California, Santa Barbara, California, USA.|Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA.
authors.forename: Stuart C
authors.initials: SC
authors.lastname: Feinstein
mesh_terms: D000595:Amino Acid Sequence / Q000502:physiology; D000818:Animals; D019281:Dimerization; D006801:Humans; D013058:Mass Spectrometry; D018625:Microscopy, Atomic Force; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D016875:tau Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D010455:Peptides; D016875:tau Proteins
keywords: Alzheimer's; Ferguson analysis; atomic force microscopy; ion mobility-mass spectrometry; microtubule dynamics; oligomerization