Aggregation and neurotoxicity of mutant amyloid β (Aβ) peptides with proline replacement: importance of turn formation at positions 22 and 23

Morimoto, Akira; Irie, Kazuhiro; Murakami, Kazuma; Ohigashi, Hajime; Shindo, Mayumi; Nagao, Masaya; Shimizu, Takahiko; Shirasawa, Takuji

doi:10.1016/s0006-291x(02)00670-8

Cited by 55 publications

(77 citation statements)

References 20 publications

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“…This result is consistent with studies showing that the optimal length of an extended chain in antiparallel ␤-sheet is seven (31). If the oligoGln sequences spanning PG elements in these peptides exist in extended-chain ␤-sheets in the aggregated state, then introduction of a single additional Pro residue at the midpoint of one of the extended-chain elements should significantly diminish aggregation (25,27,28). Fig.…”

Section: Resultssupporting

confidence: 91%

“…1). This tolerance for appropriately placed Pro residues is in contrast to the elimination of amyloid formation when a Pro residue is placed in a presumed extended-chain region of an amyloidogenic polypeptide (25,27,28). The simplest explanation for the ability of PGQ 9 to form aggregates so readily is that the peptide folds in the aggregate in such as way as to place the PG elements into turn regions where they are tolerated (23).…”

Section: Resultsmentioning

confidence: 99%

“…Proline residues are strongly disfavored in interior strands of ␤-sheet, ‡ are only rarely found in amyloidogenic sequences (25), and very efficiently block amyloid formation when inserted into amyloidogenic sequences (25). These observations led to the suggestion that Pro residues might have been used in molecular evolution to suppress off-pathway aggregation (25,26), and to the use of scanning proline mutagenesis to evaluate amyloidogenic sequences (25,27,28).…”

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confidence: 99%

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Mutational analysis of the structural organization of polyglutamine aggregates

Thakur

Wetzel

2002

Proc. Natl. Acad. Sci. U.S.A.

197

232

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The formation of amyloid-like aggregates by expanded polyglutamine (polyGln) sequences is suspected to play a critical role in the neuropathology of Huntington's disease and other expanded CAGrepeat diseases. To probe the folding of the polyGln sequence in the aggregate, we replaced Gln-Gln pairs at different sequence intervals with Pro-Gly pairs, elements that are compatible with ␤-turn formation and incompatible with ␤-extended chain. We find that PGQ9 and PGQ 10 , peptides consisting of four Q 9 or Q 10 elements interspersed with PG elements, undergo spontaneous aggregation as efficiently as a Q45 sequence, whereas the corresponding PGQ7 and PGQ8 peptides aggregate much less readily. Furthermore, a PDGQ9 sequence containing D-prolines aggregates more efficiently than the peptide with L-prolines, consistent with ␤-turn formation in aggregate structure. Introduction of one additional Pro residue in the center of a Q9 element within PGQ9 completely blocks the peptide's ability to aggregate. This strongly suggests that the Q9 elements are required to be in extended chain for efficient aggregation to occur. We determined the critical nucleus for aggregation nucleation of the PGQ9 peptide to be one, a result identical to that for unbroken polyGln sequences. The PGQN peptide aggregates are structurally quite similar to Q45 aggregates, as judged by heterologous seeding aggregation kinetics, recognition by an anti-polyGln aggregate antibody, and electron microscopy. The results suggest that polyGln aggregate structure consists of alternating elements of extended chain and turn. In the future it should be possible to conduct detailed and interpretable mutational studies in the PGQ9 background.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Mutational analysis of the structural organization of polyglutamine aggregates

Thakur

Wetzel

2002

Proc. Natl. Acad. Sci. U.S.A.

197

232

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“…Sedimentation Assay for Fibril Formation-Each A␤ derivative was dissolved in 0.02% NH 4 OH at 250 M. After a 10-fold dilution by 50 mM sodium phosphate containing 100 mM NaCl at pH 7.4, the resultant peptide solution (25 M) was incubated at 37°C for 4,8,16,24, or 48 h. After centrifugation at 15,000 rpm in an Eppendorf microcentrifuge at 4°C for 10 min, 25 l of the supernatant was then analyzed by HPLC as reported previously (15,21,22). The area of the absorption at 220 nm was integrated and expressed as a percentage of the control.…”

Section: Methodsmentioning

confidence: 99%

“…However, there are few reports on the structure of A␤42 aggregates that are more important in AD, possibly because efficient synthesis of A␤42 with 14 hydrophobic and bulky amino acid residues at the C terminus is quite difficult (11). The weak point of solid-state NMR is that it requires a series of 13 Cand/or 15 N-labeled A␤ peptides at different positions in large quantity (20 -30 mg).…”

mentioning

confidence: 99%

Analysis of the Secondary Structure of β-Amyloid (Aβ42) Fibrils by Systematic Proline Replacement

Morimoto

Irie

Murakami

et al. 2004

Journal of Biological Chemistry

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169

207

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Amyloid fibrils in Alzheimer's disease mainly consist of 40-and 42-mer ␤-amyloid peptides (A␤40 and A␤42) that exhibit aggregative ability and neurotoxicity. Although the aggregates of A␤ peptides are rich in intermolecular ␤-sheet, the precise secondary structure of A␤ in the aggregates remains unclear. To identify the amino acid residues involved in the ␤-sheet formation, 34 proline-substituted mutants of A␤42 were synthesized and their aggregative ability and neurotoxicity on PC12 cells were examined. Prolines are rarely present in ␤-sheet, whereas they are easily accommodated in ␤-turn as a Pro-X corner. Among the mutants at positions 15-32, only E22P-A␤42 extensively aggregated with stronger neurotoxicity than wild-type A␤42, suggesting that the residues at positions 15-21 and 24 -32 are involved in the ␤-sheet and that the turn at positions 22 and 23 plays a crucial role in the aggregation and neurotoxicity of A␤42. The C-terminal proline mutants (A42P-, I41P-, and V40P-A␤42) hardly aggregated with extremely weak cytotoxicity, whereas the C-terminal threonine mutants (A42T-and I41T-A␤42) aggregated potently with significant cytotoxicity. These results indicate that the hydrophobicity of the C-terminal two residues of A␤42 is not related to its aggregative ability and neurotoxicity, rather the C-terminal three residues adopt the ␤-sheet. These results demonstrate well the large difference in aggregative ability and neurotoxicity between A␤42 and A␤40. In contrast, the proline mutants at the N-terminal 13 residues showed potent aggregative ability and neurotoxicity similar to those of wild-type A␤42. The identification of the ␤-sheet region of A␤42 is a basis for designing new aggregation inhibitors of A␤ peptides. Alzheimer's disease (AD)1 is neuropathologically characterized by the progressive deposition of amyloid fibrils in the brain parenchyma and cortical blood vessels (1). This deposition mainly consists of 40-and 42-mer peptides (A␤40 and A␤42) generated from amyloid precursor protein by two proteases, ␤-and ␥-secretase (2, 3). A␤42 plays a pivotal role in the pathogenesis of AD, because the aggregative ability and neurotoxicity of A␤42 are considerably higher than those of A␤40 (4). Because the aggregative ability of A␤ peptides is closely related to the neurotoxicity, precise structural information for amyloid fibrils is indispensable for understanding the molecular mechanisms of AD and related folding diseases and for developing new medicinal leads using the inhibitory activity of amyloid fibril formation.Previous studies on A␤ fibrils showed that A␤ aggregates mainly consist of intermolecular parallel ␤-sheet (5-10

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N‐terminal truncated pyroglutamyl β amyloid peptide Aβpy3‐42 shows a faster aggregation kinetics than the full‐length Aβ1‐42

2009

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We tested directly the differences in the aggregation kinetics of three important beta amyloid peptides, the full-length Abeta1-42, and the two N-terminal truncated and pyroglutamil modified Abetapy3-42 and Abetapy11-42 found in different relative concentrations in the brains in normal aging and in Alzheimer disease. By following the circular dichroism signal and the ThT fluorescence of the solution in phosphate buffer, we found substantially faster aggregation kinetics for Abetapy3-42. This behavior is due to the particular sequence of this peptide, which is also responsible for the specific oligomeric aggregation states, found by TEM, during the fibrillization process, which are very different from those of Abeta1-42, more prone to fibril formation. In addition, Abetapy3-42 is found here to have an inhibitory effect on Abeta1-42 fibrillogenesis, coherently with its known greater infective power. This is an indication of the important role of this peptide in the aggregation process of beta-peptides in Alzheimer disease.

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Aggregation and neurotoxicity of mutant amyloid β (Aβ) peptides with proline replacement: importance of turn formation at positions 22 and 23

Cited by 55 publications

References 20 publications

Mutational analysis of the structural organization of polyglutamine aggregates

Mutational analysis of the structural organization of polyglutamine aggregates

Analysis of the Secondary Structure of β-Amyloid (Aβ42) Fibrils by Systematic Proline Replacement

N‐terminal truncated pyroglutamyl β amyloid peptide Aβpy3‐42 shows a faster aggregation kinetics than the full‐length Aβ1‐42

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