Folding of Alzheimer's core PHF subunit revealed by monoclonal antibody 423

Škrabana, Rostislav; Kontsek, Peter; Mederlyova, Anna; Iqbal, Khalid; Novák, Michal

doi:10.1016/j.febslet.2004.04.098

Cited by 43 publications

(34 citation statements)

References 19 publications

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“…In the soluble state of tau conformationally dependent antibodies indicate an interaction of the C-terminus and the repeat region (antibody MN423 reacts against a truncation site downstream of the repeats at E391) and residues within the repeat domain (49) and by indirect approaches measuring the polymerization of tau molecules with and without the C-terminus (22). We confirmed an interaction between these regions by FRET of soluble tau with FRET pairs spanning the distance from the repeats to the C-terminus (50).…”

Section: Discussionmentioning

confidence: 99%

The Core of Tau-Paired Helical Filaments Studied by Scanning Transmission Electron Microscopy and Limited Proteolysis

et al. 2006

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In Alzheimer's disease and frontotemporal dementias the microtubule-associated protein tau forms intracellular paired helical filaments (PHFs). The filaments formed in vivo consist mainly of fulllength molecules of the six different isoforms present in adult brain. The substructure of the PHF core is still elusive. Here we applied scanning transmission electron microscopy (STEM) and limited proteolysis to probe the mass distribution of PHFs and their surface exposure. Tau filaments assembled from the three repeat domain have a mass per length (MPL) of ∼60 kDa/nm and filaments from full-length tau (htau40∆K280 mutant) have ∼160 kDa/nm, compared with ∼130 kDa/nm for PHFs from Alzheimer's brain. Polyanionic cofactors such as heparin accelerate assembly but are not incorporated into PHFs. Limited proteolysis combined with N-terminal sequencing and mass spectrometry of fragments reveals a protease-sensitive N-terminal half and semiresistant PHF core starting in the first repeat and reaching to the C-terminus of tau. Continued proteolysis leads to a fragment starting at the end of the first repeat and ending in the fourth repeat. PHFs from tau isoforms with four repeats revealed an additional cleavage site within the middle of the second repeat. Probing the PHFs with antibodies detecting epitopes either over longer stretches in the C-terminal half of tau or in the fourth repeat revealed that they grow in a polar manner. These data describe the physical parameters of the PHFs and enabled us to build a model of the molecular arrangement within the filamentous structures.Alzheimer's disease is characterized by the coexistence of two different amyloid deposits in the brain, the extracellular senile plaques composed of fibrils of A peptides and the intracellular paired helical filaments (PHFs) 1 consisting mostly of the microtubule-associated protein tau. Tau is expressed in the adult brain in six isoforms which differ by the presence of two inserts in the N-terminal part (exons 2 and 3) and the second repeat R2 (exon 10) in the repeat domain (Figure 1). The physiological function of tau is to bind and stabilize axonal microtubules. The soluble form of tau has a mostly random coil conformation (1, 2) and thus belongs to the emerging group of natively unfolded proteins (3)(4)(5). Whereas the aggregation of the A peptide can be explained in part by its hydrophobic character, this cannot by applied to tau, which has an overall hydrophilic character and is unusually well soluble. However, tau contains short motifs in the repeat domain which are weakly hydrophobic.

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Section: Discussionmentioning

confidence: 99%

The Core of Tau-Paired Helical Filaments Studied by Scanning Transmission Electron Microscopy and Limited Proteolysis

et al. 2006

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“…We have hypothesized that truncation could play major role in AD tau pathology [11]. This hypothesis originated from finding that AD-specific monoclonal antibody 423 (mAb 423) recognizes truncated tau species in the core of paired helical filaments (PHF) of Alzheimer's disease [5,6,12,13]. Furthermore, mAb DC11, raised against sporadic AD-brain derived tau extracts, recognized all and only those tau proteins that were truncated at the N-terminus or at both, the N-and C-termini [8].…”

Section: Introductionmentioning

confidence: 99%

Truncated tau from sporadic Alzheimer's disease suffices to drive neurofibrillary degeneration in vivo

Žilka¹,

Filipčík²,

Koson³

et al. 2006

FEBS Letters

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203

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Truncated tau protein is the characteristic feature of human sporadic Alzheimer's disease. We have identified truncated tau proteins conformationally different from normal healthy tau. Subpopulations of these structurally different tau species promoted abnormal microtubule assembly in vitro suggesting toxic gain of function. To validate pathological activity in vivo we expressed active form of human truncated tau protein as transgene, in the rat brain. Its neuronal expression led to the development of the neurofibrillary degeneration of Alzheimer's type. Furthermore, biochemical analysis of neurofibrillary changes revealed that massive sarcosyl insoluble tau complexes consisted of human Alzheimer's tau and endogenous rat tau in ratio 1:1 including characteristic Alzheimer's disease (AD)-specific proteins (A68). This work represents first insight into the possible causative role of truncated tau in AD neurofibrillary degeneration in vivo.

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“…They argue that there is some interaction between different domains of tau, e.g. between the N-terminal domain and the repeats, or between the C-terminal domain and the repeats [46][47][48] . To detect long-range interactions we followed a FRET-based approach, creating single tryptophan and cysteine mutants in tau.…”

Section: Long-range Structure In Taumentioning

confidence: 99%

Spectroscopic Approaches to the Conformation of Tau Protein in Solution and in Paired Helical Filaments

et al. 2006

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The abnormal aggregation of the microtubule-associated protein tau into paired helical filaments is one the hallmarks of Alzheimer’s disease. This aggregation is based in the partial formation of β-structure. In contrast, the soluble protein shows a mostly random coil structure, as judged by circular dichroism, Fourier transform infrared, X-ray scattering and biochemical assays. Here, we review the basis of the natively unstructured character of tau, as well as recent studies of residual structure and long-range interactions between different domains of the protein. Analysis of the primary structure reveals a very low content of hydrophobic amino acids and a high content of charged residues, both of which tend to counteract a well-folded globular state of proteins. In the case of tau, the low overall hydrophobicity is sufficient to explain the lack of folding. This is in contrast to other proteins which also carry an excess charge at physiological pH. By tryptophan scanning mutagenesis and fluorimetry we found that most of the sequence is solvent exposed. Analysis of the hydrodynamic radii confirms a mostly random coil structure of various tau isoforms and tau domains. The proteins can be further expanded by denaturation with GdHCl which indicates some global folding. This was substantiated by a FRET-based approach where the distances between different domains of tau were determined. The combined data show that tau is mostly disordered and flexible but tends to assume a hairpin-like overall fold which may be important in the transition to a pathological aggregate.

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Folding of Alzheimer's core PHF subunit revealed by monoclonal antibody 423

Cited by 43 publications

References 19 publications

The Core of Tau-Paired Helical Filaments Studied by Scanning Transmission Electron Microscopy and Limited Proteolysis

The Core of Tau-Paired Helical Filaments Studied by Scanning Transmission Electron Microscopy and Limited Proteolysis

Truncated tau from sporadic Alzheimer's disease suffices to drive neurofibrillary degeneration in vivo

Spectroscopic Approaches to the Conformation of Tau Protein in Solution and in Paired Helical Filaments

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