Tissue Transglutaminase-mediated Glutamine Deamidation of -Amyloid Peptide Increases Peptide Solubility, Whereas Enzymatic Cross-linking and Peptide Fragmentation May Serve as Molecular Triggers for Rapid Peptide Aggregation
ABSTRACT Tissue transglutaminase (TGase) has been implicated in a number of cellular processes and disease states, where the enzymatic actions of TGase may serve in both, cell survival and apoptosis. To date, the precise functional properties of TGase in cell survival or cell death mechanisms still remain elusive. TGase-mediated cross-linking has been reported to account for the formation of insoluble lesions in conformational diseases. We report here that TGase induces intramolecular cross-linking of β-amyloid peptide (Aβ), resulting in structural changes of monomeric Aβ. Using high resolution mass spectrometry (MS) of cross-linked Aβ peptides, we observed a shift in mass, which is, presumably associated with the loss of NH3 due to enzymatic transamidation activity and hence intramolecular peptide cross-linking. We have observed that a large population of Aβ monomers contained an 0.984 Da increase in mass at a glutamine residue, indicating that glutamine 15 serves as an indispensable substrate in TGase-mediated deamidation to glutamate 15. We provide strong analytical evidence on TGase-mediated Aβ peptide dimerization, through covalent intermolecular cross-linking and hence the formation of Aβ1-40 dimers. Our in depth analyses indicate that TGase-induced post-translational modifications of Aβ peptide may serve as an important seed for aggregation.
- SourceAvailable from: Micha Wilhelmus
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- "In AD brain, tTG levels and its cross-links are elevated (Appelt et al., 1996; Johnson et al., 1997; Wang et al., 2008b) and correlate with the cognitive decline observed in these patients (Sárvári et al., 2002; Wang et al., 2008b). Furthermore, tTG binds to Ab, and tTG-mediated cross-linking modulates the Ab aggregation pathway (Dudek and Johnson, 1994; Ikura et al., 1993; Rasmussen et al., 1994; Schmid et al., 2011). In fact, a recent study demonstrated that tTG activity is able to induce formation of neurotoxic and protease resistant Ab complexes at low, i.e., nanomolar, concentrations of Ab (Hartley et al., 2008). "
ABSTRACT: Cerebral amyloid angiopathy (CAA) is a key histopathological hallmark of Alzheimer's disease (AD) and hereditary cerebral hemorrhage with amyloidosis of the Dutch type (HCHWA-D). CAA is characterized by amyloid-beta (Aβ) depositions and remodeling of the extracellular matrix (ECM) in brain vessels and plays an important role in the development and progression of both AD and HCHWA-D. Tissue transglutaminase (tTG) modulates the ECM by molecular cross-linking of ECM proteins. Here, we investigated the distribution pattern, cellular source, and activity of tTG in CAA in control, AD, and HCHWA-D cases. We observed increased tTG immunoreactivity and colocalization with Aβ in the vessel wall in early stage CAA, whereas in later CAA stages, tTG and its cross-links were present in halos enclosing the Aβ deposition. In CAA, tTG and its cross-links at the abluminal side of the vessel were demonstrated to be either of astrocytic origin in parenchymal vessels, of fibroblastic origin in leptomeningeal vessels, and of endothelial origin at the luminal side of the deposited Aβ. Furthermore, the ECM proteins fibronectin and laminin colocalized with the tTG-positive halos surrounding the deposited Aβ in CAA. However, we observed that in situ tTG activity was present throughout the vessel wall in late stage CAA. Together, our data suggest that tTG and its activity might play a differential role in the development and progression of CAA, possibly evolving from direct modulation of Aβ aggregation to cross-linking of ECM proteins resulting in ECM restructuring.Neurobiology of aging 10/2012; 44(4). DOI:10.1016/j.neurobiolaging.2012.10.005 · 5.01 Impact Factor
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- "In the absence of primary amines, water can act as an acyl acceptor, which results in the deamidation of glutamine residues (Yokoyama et al., 2004). Multifunctional TGases are widely found in mammals (Schmid et al., 2011), plants (Carvajal et al., 2011), and microorganisms (Yokoyama et al., 2004). The first microbial TGase was discovered in Streptomyces mobaraensis (Ando et al., 1989). "
ABSTRACT: Streptomyces transglutaminase (TGase) is secreted as a zymogen (pro-TGase) in liquid cultures and is then processed by the removal of its N-terminal region, resulting in active TGase. To date, there is no report describing TGase (or pro-TGase) secretion in Escherichia coli. In this study, the pro-TGase from Streptomyces hygroscopicus was efficiently secreted by E. coli BL21(DE3) using the TGase signal peptide or the pelB signal peptide. The secreted pro-TGase was efficiently transformed into active TGase by adding dispase to the culture supernatant of the recombinant strains. Mutational analysis showed that deletion of the first six amino acids of the N-terminal of the pro-region reduced the secretion of pro-TGase, and removal of the next 10 amino acids resulted in the formation of insoluble pro-TGase. These results suggest that the pro-region of TGase is essential for its efficient secretion and solubility in E. coli.FEMS Microbiology Letters 11/2011; 324(2):98-105. DOI:10.1111/j.1574-6968.2011.02387.x · 2.12 Impact Factor
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- "Possible mechanisms responsible for protein aggregate formation catalyzed by transglutaminases Transglutaminases and neurodegenerative diseases 115 proteins (Verhoef et al. 2002) and that transglutaminasecatalyzed cross-linking of b-amyloid peptide may serve as trigger for rapid peptide aggregation (Schmid et al. 2011). "
ABSTRACT: Transglutaminases are ubiquitous enzymes, which catalyze post-translational modifications of proteins. Recently, transglutaminases and tranglutaminase-catalyzed post-translational modification of proteins have been shown to be involved in the molecular mechanisms responsible for several human diseases. Transglutaminase activity has been hypothesized to be involved also in the pathogenetic mechanisms responsible for human neurodegenerative diseases. Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, supranuclear palsy, Huntington's disease and other polyglutamine diseases, are characterized in part by aberrant cerebral transglutaminase activity and by increased cross-linked proteins in affected brains. In this review, we focus on the possible molecular mechanisms by which transglutaminase activity could be involved in the pathogenesis of neurodegenerative diseases, and on the possible therapeutic effects of selective transglutaminase inhibitors for the cure of patients with diseases characterized by aberrant transglutaminase activity.Amino Acids 09/2011; 44(1). DOI:10.1007/s00726-011-1081-1 · 3.29 Impact Factor