The interplay of glycosylation and disulfide formation influences  fibrillization in a prion protein fragment

Bosques, Carlos J.; Imperiali, Barbara

doi:10.1073/pnas.1232504100

Cited by 74 publications

(57 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the structural point of view, the C-terminal domain has to expand its known conformational repertoire to accommodate the absence of the ␣2-␣3 constraint and a double tether to the membrane (51,52,61). Also, the fibrillation of CtmPrP may be impeded by the diglycosylation (52,62). But the detergent insolubility of CtmPrP suggests that it may populate distinct aggregate states, adding more structural complexity.…”

Section: Discussionmentioning

confidence: 99%

Failure of Prion Protein Oxidative Folding Guides the Formation of Toxic Transmembrane Forms

Lisa

Domingo

Martínez

et al. 2012

Journal of Biological Chemistry

View full text Add to dashboard Cite

Background:In vivo folding could play an essential role in prion neurodegenerations. Results: Artificial mutants causing labile PrP folds when expressed in cells originate toxic CtmPrP featured by the absence of the intramolecular disulfide bond. Conclusion: Oxidative folding impairment facilitates the formation of the toxic PrP forms. Significance: Unveiling the mechanism facilitating the formation of toxic PrP forms is crucial for the understanding and prevention of prion disorders.The mechanism by which pathogenic mutations in the globular domain of the cellular prion protein (PrP C ) increase the likelihood of misfolding and predispose to diseases is not yet known. Differences in the evidences provided by structural and metabolic studies of these mutants suggest that in vivo folding could be playing an essential role in their pathogenesis. To address this role, here we use the single or combined M206S and M213S artificial mutants causing labile folds and express them in cells. We find that these mutants are highly toxic, fold as transmembrane PrP, and lack the intramolecular disulfide bond. When the mutations are placed in a chain with impeded transmembrane PrP formation, toxicity is rescued. These results suggest that oxidative folding impairment, as on aging, can be fundamental for the genesis of intracellular neurotoxic intermediates key in prion neurodegenerations.Prion disorders are dominant gain-of-function neurodegenerations whose pathogenesis is linked to misfolded forms of the cellular prion protein (PrP C ), 3 including the prion PrP Sc and the neurotoxic CtmPrP (1-4). PrPSc is an aggregated and proteaseresistant ␤-sheet-enriched conformer of PrP C , which self-perpetuates by the templating the conversion of cell surface PrP C (1, 4). In contrast, CtmPrP is an intracellular transmembrane form generated at the ER with neurotoxic properties (1,5,6). Despite that CtmPrP formation was associated with features of the ER translocation process several pathogenic mutations in the C-terminal domain such as H187R and E200K enhance its levels, suggesting a yet unexplored in vivo interplay between folding and the accumulation and action of this neurotoxic form (6 -8).Since the enunciation of the prion hypothesis, research has focused on the mechanism by which a native PrP C structure reorganizes and acquires self-propagative features like those of PrP Sc (9 -11). The PrP C native state was assigned to the fold adopted by the chain lacking the signal sequences and containing the disulfide bond and used as reference for testing the effect of pathogenic mutations and its conversion into active prions (10,(12)(13)(14)(15)(16). However, the in vivo folding of proteins segregating into the secretory route such as PrP is a complex process participated by the ER folding machinery. This machinery coordinates processing (signal sequences removal, addition of covalent modifications, binding of cofactors, etc.), avoids undesired aggregations, and permits the acquisition of correct structure. This global process involves m...

show abstract

Section: Discussionmentioning

confidence: 99%

Failure of Prion Protein Oxidative Folding Guides the Formation of Toxic Transmembrane Forms

Lisa

Domingo

Martínez

et al. 2012

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…These amyloid fibrils, straight and unbranched, viewed under transmission electron microscope (5), can be detected through the binding of dyes such as thioflavin T (ThT) 2 (6) or Congo Red (7). Furthermore, amyloid formation arises primarily from the main chain interaction (8), and disulfide bonds in proteins usually play an essential role in amyloid fibril formation (9,10).…”

mentioning

confidence: 99%

Deficiency of Disulfide Bonds Facilitating Fibrillogenesis of Endostatin

Zhou

Tang

et al. 2006

Journal of Biological Chemistry

View full text Add to dashboard Cite

Endostatin is an endogenous inhibitor of tumor angiogenesis and tumor growth. It has two pairs of disulfide bonds in a unique nested pattern, which play a key role in its native conformation, stability, and activity. Here, we constructed a disulfide-deficient variant of endostatin, endo-all-Ala, to examine the effects of the two disulfide bonds on fibrillogenesis of endostatin under nondenaturing conditions. Based on thioflavin T fluorescence, atomic force microscopy, far-UV circular dichroism, and Fourier transform infrared spectroscopy, we found that endo-all-Ala, which has a higher ␣-helical content compared with wild type, is prone to forming fibrils in a pH-dependent manner. Subsequently, more hydrophobic patches with a lower stability of endo-all-Ala were observed when compared with wild type, which possibly contributes to the propensity of amyloid formation of endo-all-Ala. To our surprise, the significant increase of the ␣-helical content in endostatin induced by trifluoroethanol can also facilitate fibril formation. In addition, the cytotoxicity of fibrillar aggregates of endo-all-Ala, which were generated at different stages of the fibril formation process, was evaluated by cell viability assay. The results indicate that the cytotoxicity is not due to the fibrils but rather due to the granular aggregates of endo-all-Ala. Moreover, endostatin was interestingly found to be reduced by glutathione at physiological concentrations. Our present work not only elucidates the correlation between the existence of disulfide bonds and the fibril formation of endostatin but also may provide some insights into the structural and functional basis of endostatin in Alzheimer disease brains.Formation of amyloid-like fibrils is frequently considered to be a generic property of many proteins (1, 2), including but not limited to disease-related proteins (3, 4). Although having no obvious amino acid sequence similarity, all amyloid fibrils appear to share a common characteristic cross-␤-sheet structure that forms the core of the fibrils (5). These amyloid fibrils, straight and unbranched, viewed under transmission electron microscope (5), can be detected through the binding of dyes such as thioflavin T (ThT) 2 (6) or Congo Red (7). Furthermore, amyloid formation arises primarily from the main chain interaction (8), and disulfide bonds in proteins usually play an essential role in amyloid fibril formation (9, 10).Endostatin is a 20-kDa C-terminal fragment of collagen XVIII (11). It can specifically inhibit vascular endothelial cell proliferation and migration and thus potently prevent angiogenesis and tumor growth without induced toxicity or acquired drug resistance (11-13). Endostatin is a globular protein with two pairs of disulfide bonds (Cys 33 -Cys 173 and Cys 135 -Cys 165 ) in a unique nested pattern (14). These disulfide bonds, making the whole molecule tightly packed, are intimately related to the native conformation, stability, and activity of endostatin (15). It has been reported that endostatin is acid-resistant wi...

show abstract

“…For example, glycosylation of the prion protein PrPc has a significant effect on decelerating the rate of fibril formation (43). A similar effect is observed in the bacterial autotransporter Ag43, which has the ability to aggregate into amyloid-like structures.…”

Section: Discussionmentioning

confidence: 81%

Microcin E492 Amyloid Formation Is Retarded by Posttranslational Modification

Marcoleta

Marín

Mercado

et al. 2013

Journal of Bacteriology

View full text Add to dashboard Cite

b Microcin E492, a channel-forming bacteriocin with the ability to form amyloid fibers, is exported as a mixture of two forms: unmodified (inactive) and posttranslationally modified at the C terminus with a salmochelin-like molecule, which is an essential modification for conferring antibacterial activity. During the stationary phase, the unmodified form accumulates because expression of the maturation genes mceIJ is turned off, and microcin E492 is rapidly inactivated. The aim of this work was to demonstrate that the increase in the proportion of unmodified microcin E492 augments the ability of this bacteriocin to form amyloid fibers, which in turn decreases antibacterial activity. To this end, strains with altered proportions of the two forms were constructed. The increase in the expression of the maturation genes augmented the antibacterial activity during all growth phases and delayed the loss of activity in the stationary phase, while the ability to form amyloid fibers was markedly reduced. Conversely, a higher expression of microcin E492 protein produced concomitant decreases in the levels of the modified form and in antibacterial activity and a substantial increase in the ability to form amyloid fibers. The same morphology for these fibers, including those formed by only the unmodified version, was observed. Moreover, seeds formed using exclusively the nonmodified form were remarkably more efficient in amyloid formation with a shorter lag phase, indicating that the nucleation process is probably improved. Unmodified microcin E492 incorporation into amyloid fibers was kinetically more efficient than the modified form, probably due to the existence of a conformation that favors this process.

show abstract

The interplay of glycosylation and disulfide formation influences fibrillization in a prion protein fragment

Cited by 74 publications

References 38 publications

Failure of Prion Protein Oxidative Folding Guides the Formation of Toxic Transmembrane Forms

Failure of Prion Protein Oxidative Folding Guides the Formation of Toxic Transmembrane Forms

Deficiency of Disulfide Bonds Facilitating Fibrillogenesis of Endostatin

Microcin E492 Amyloid Formation Is Retarded by Posttranslational Modification

Contact Info

Product

Resources

About