title: Covalent blocking of fibril formation and aggregation of intracellular amyloidgenic proteins by transglutaminase-catalyzed intramolecular cross-linking.
abstract: Two different types of physical bonding have been proposed to involve in the formation of neuronal inclusions of patients with neurodegenerative diseases such as Alzheimer's, Parkinson's, and polyglutamine diseases. One is the noncovalent bonding that stabilizes the amyloid-type fibrous aggregates, and the other is the covalent cross-linking catalyzed by tissue transglutaminase. The cross-linking is subdivided into the inter- and intramolecular cross-linking. Little attention has been paid to the pathological roles of the intramolecular cross-linking. To elucidate the possible interplay between the intramolecular cross-linking and the amyloid-type fibril formation, we performed an in vitro aggregation analysis of three intracellular amyloidgenic proteins (a domain of tau protein, alpha-synuclein, and truncated yeast prion Sup35) in the presence of tissue transglutaminase. The analysis was performed in low concentrations of the proteins using techniques including thioflavin T binding and mass spectrometry. The results demonstrated that the amyloid-type fibril formation was strongly inhibited by the transglutaminase-catalyzed intramolecular cross-linking, which blocked both the nucleation and the fiber extension steps of the amyloid formation. Far-UV CD spectroscopy indicated that the cross-linking slightly altered the backbone conformation of the proteins. It is likely that conformational restriction imposed by the intramolecular cross-links has impaired the ordered assembly of the amyloidgenic proteins. Nonamyloid type aggregation was also suppressed by the intramolecular cross-links. On the basis of the results, we proposed that tissue transglutaminase is a modulator for the protein aggregation and can act defensively against the fibril deposition in neurons.
authors.affiliation: Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, Matsuoka, Yoshida, Fukui, 910-1193, Japan. konno@fmsrsa.fukui-med.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Konno
authors.forename: Takashi
authors.initials: T
authors.lastname: Morii
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Hirata
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Sato
authors.forename: Shigetoshi
authors.initials: S
authors.lastname: Oiki
authors.forename: Koji
authors.initials: K
authors.lastname: Ikura
mesh_terms: D000328:Adult; D000682:Amyloid / Q000037:antagonists & inhibitors* / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D002384:Catalysis; D002417:Cattle; D002850:Chromatography, Gel; D003432:Cross-Linking Reagents / Q000737:chemistry / Q000378:metabolism*; D006168:Guinea Pigs; D006801:Humans; D007424:Intracellular Fluid / Q000201:enzymology* / Q000378:metabolism; D007782:Lactoglobulins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010454:Peptide Termination Factors; D011328:Prions / Q000378:metabolism; D017434:Protein Structure, Tertiary; D020449:Repetitive Sequences, Amino Acid; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D051843:Synucleins; D011503:Transglutaminases / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D051844:alpha-Synuclein; D016875:tau Proteins / Q000378:metabolism
chemical_list: D000682:Amyloid; D003432:Cross-Linking Reagents; D007782:Lactoglobulins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D010454:Peptide Termination Factors; D011328:Prions; C497604:SNCA protein, human; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D051843:Synucleins; D051844:alpha-Synuclein; D016875:tau Proteins; D011503:Transglutaminases