Dual modification of Alzheimer's disease PHF-tau protein by lysine methylation and ubiquitylation: a mass spectrometry approach.

05:50 EDT 21st April 2015 | BioPortfolio

Summary of "Dual modification of Alzheimer's disease PHF-tau protein by lysine methylation and ubiquitylation: a mass spectrometry approach."

In sporadic Alzheimer's disease (AD), neurofibrillary lesion formation is preceded by extensive post-translational modification of the microtubule associated protein tau. To identify the modification signature associated with tau lesion formation at single amino acid resolution, immunopurified paired helical filaments were isolated from AD brain and subjected to nanoflow liquid chromatography-tandem mass spectrometry analysis. The resulting spectra identified monomethylation of lysine residues as a new tau modification. The methyl-lysine was distributed among seven residues located in the projection and microtubule binding repeat regions of tau protein, with one site, K254, being a substrate for a competing lysine modification, ubiquitylation. To characterize methyl lysine content in intact tissue, hippocampal sections prepared from post mortem late-stage AD cases were subjected to double-label confocal fluorescence microscopy using anti-tau and anti-methyl lysine antibodies. Anti-methyl lysine immunoreactivity colocalized with 78 ± 13% of neurofibrillary tangles in these specimens. Together these data provide the first evidence that tau in neurofibrillary lesions is post-translationally modified by lysine methylation.

Affiliation

Greenebaum Cancer Center, University of Maryland, Baltimore, MD, 21201, USA.

Journal Details

This article was published in the following journal.

Name: Acta neuropathologica
ISSN: 1432-0533
Pages:

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Medical and Biotech [MESH] Definitions

The specific patterns of POST-TRANSLATIONAL PROTEIN MODIFICATION of HISTONES, i.e. histone ACETYLATION; METHYLATION; PHOSPHORYLATION; and ubiquitination, at specific amino acid residues, that are involved in assembly, maintenance, and modification of different chromatin structural states, such as EUCHROMATIN and HETEROCHROMATIN.

An enzyme that catalyzes the methylation of the epsilon-amino group of lysine residues in proteins to yield epsilon mono-, di-, and trimethyllysine. EC 2.1.1.43.

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Post-transcriptional biological modification of messenger, transfer, or ribosomal RNAs or their precursors. It includes cleavage, methylation, thiolation, isopentenylation, pseudouridine formation, conformational changes, and association with ribosomal protein.

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