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Analysis of core region from egg white lysozyme forming amyloid fibrils.

Tokunaga Y, Sakakibara Y, Kamada Y, Watanabe K, Sugimoto Y - Int. J. Biol. Sci. (2013)

Bottom Line: The K peptide alone formed definite fibrils having β-sheet structures by incubation of 7 days under acidic conditions at 37°C.A substantial number of fibrils were generated under this pH condition and incubation period.Deletion and substitution of tryptophan in the K peptide resulted in no formation of fibrils.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biochemistry and Bioscience The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890-0065 Japan.

ABSTRACT
Some of the lysozyme mutants in humans cause systemic amyloidosis. Hen egg white lysozyme (HEWL) has been well studied as a model protein of amyloid fibrils formation. We previously identified an amyloid core region consisting of nine amino acids (designated as the K peptide), which is present at 54-62 in HEWL. The K peptide, with tryptophan at its C- terminus, has the ability of self-aggregation. In the present work we focused on its structural properties in relation to the formation of fibrils. The K peptide alone formed definite fibrils having β-sheet structures by incubation of 7 days under acidic conditions at 37°C. A substantial number of fibrils were generated under this pH condition and incubation period. Deletion and substitution of tryptophan in the K peptide resulted in no formation of fibrils. Tryptophan 62 in lysozyme was suggested to be especially crucial to forming amyloid fibrils. We also show that amyloid fibrils formation of the K peptide requires not only tryptophan 62 but also a certain length containing hydrophobic amino acids. A core region is involved in the significant formation of amyloid fibrils of lysozyme.

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AFM and TEM images of the K peptide in comparison with other substances. A (K pep-7), the K peptide incubated for 7 days at pH 4.0; B (HEWL-14), HEWL incubated for 14 days at pH 2.0; C (STDY-K-7), the STDY-K peptide incubated for 7 days at pH 2.0; D (KW62G-7), GILQINSRG (the W-substituted K peptide) incubated for 7 days at pH 2.0. The concentration of each peptide and HEWL during analysis was 2 mg/ml (cf. Materials and Methods).
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Figure 3: AFM and TEM images of the K peptide in comparison with other substances. A (K pep-7), the K peptide incubated for 7 days at pH 4.0; B (HEWL-14), HEWL incubated for 14 days at pH 2.0; C (STDY-K-7), the STDY-K peptide incubated for 7 days at pH 2.0; D (KW62G-7), GILQINSRG (the W-substituted K peptide) incubated for 7 days at pH 2.0. The concentration of each peptide and HEWL during analysis was 2 mg/ml (cf. Materials and Methods).

Mentions: Inspection by AFM and TEM (Fig. 3) indicated that the fibrils found in the K peptide preparation on day 7 of incubation at pH 4 had a typical amyloid morphology (panels A). The fibrils produced from the K peptide at pH 2 showed similar patterns (not shown). These contained short and twisting fibrils with a diameter of ca. 5-10 nm, resembling the amyloid fibrils of HEWL observed after incubation for 14 days at pH 2 (panels B). The STDY-K peptide (see above) after incubation in acidic milieu also produced amyloidal patterns, while the K peptide mutant GILQINSRG gave no aggregation after incubation at all pHs tested (panels C and D, respectively; both show pH 2 preparations after day 7 of incubation).


Analysis of core region from egg white lysozyme forming amyloid fibrils.

Tokunaga Y, Sakakibara Y, Kamada Y, Watanabe K, Sugimoto Y - Int. J. Biol. Sci. (2013)

AFM and TEM images of the K peptide in comparison with other substances. A (K pep-7), the K peptide incubated for 7 days at pH 4.0; B (HEWL-14), HEWL incubated for 14 days at pH 2.0; C (STDY-K-7), the STDY-K peptide incubated for 7 days at pH 2.0; D (KW62G-7), GILQINSRG (the W-substituted K peptide) incubated for 7 days at pH 2.0. The concentration of each peptide and HEWL during analysis was 2 mg/ml (cf. Materials and Methods).
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3584918&req=5

Figure 3: AFM and TEM images of the K peptide in comparison with other substances. A (K pep-7), the K peptide incubated for 7 days at pH 4.0; B (HEWL-14), HEWL incubated for 14 days at pH 2.0; C (STDY-K-7), the STDY-K peptide incubated for 7 days at pH 2.0; D (KW62G-7), GILQINSRG (the W-substituted K peptide) incubated for 7 days at pH 2.0. The concentration of each peptide and HEWL during analysis was 2 mg/ml (cf. Materials and Methods).
Mentions: Inspection by AFM and TEM (Fig. 3) indicated that the fibrils found in the K peptide preparation on day 7 of incubation at pH 4 had a typical amyloid morphology (panels A). The fibrils produced from the K peptide at pH 2 showed similar patterns (not shown). These contained short and twisting fibrils with a diameter of ca. 5-10 nm, resembling the amyloid fibrils of HEWL observed after incubation for 14 days at pH 2 (panels B). The STDY-K peptide (see above) after incubation in acidic milieu also produced amyloidal patterns, while the K peptide mutant GILQINSRG gave no aggregation after incubation at all pHs tested (panels C and D, respectively; both show pH 2 preparations after day 7 of incubation).

Bottom Line: The K peptide alone formed definite fibrils having β-sheet structures by incubation of 7 days under acidic conditions at 37°C.A substantial number of fibrils were generated under this pH condition and incubation period.Deletion and substitution of tryptophan in the K peptide resulted in no formation of fibrils.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biochemistry and Bioscience The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890-0065 Japan.

ABSTRACT
Some of the lysozyme mutants in humans cause systemic amyloidosis. Hen egg white lysozyme (HEWL) has been well studied as a model protein of amyloid fibrils formation. We previously identified an amyloid core region consisting of nine amino acids (designated as the K peptide), which is present at 54-62 in HEWL. The K peptide, with tryptophan at its C- terminus, has the ability of self-aggregation. In the present work we focused on its structural properties in relation to the formation of fibrils. The K peptide alone formed definite fibrils having β-sheet structures by incubation of 7 days under acidic conditions at 37°C. A substantial number of fibrils were generated under this pH condition and incubation period. Deletion and substitution of tryptophan in the K peptide resulted in no formation of fibrils. Tryptophan 62 in lysozyme was suggested to be especially crucial to forming amyloid fibrils. We also show that amyloid fibrils formation of the K peptide requires not only tryptophan 62 but also a certain length containing hydrophobic amino acids. A core region is involved in the significant formation of amyloid fibrils of lysozyme.

Show MeSH
Related in: MedlinePlus