Effects of chain length of an amphipathic polypeptide carrying the repeated amino acid sequence (LETLAKA)n on α-helix and fibrous assembly formation

Toshiaki Takei, Kazuya Hasegawa, Katsumi Imada, Keiichi Namba, Kouhei Tsumoto, Yukino Kuriki, Masakuni Yoshino, Kazumori Yazaki, Shuichi Kojima, Tsunetomo Takei, Takuya Ueda, Kin Ichiro Miura

Research output: Contribution to journalArticle

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Abstract

Polypeptide α3 (21 residues), with three repeats of a seven-amino-acid sequence (LETLAKA)3, forms an amphipathic α-helix and a long fibrous assembly. Here, we investigated the ability of α3-series polypeptides (with 14-42 residues) of various chain lengths to form α-helices and fibrous assemblies. Polypeptide α2 (14 residues), with two same-sequence repeats, did not form an α-helix, but polypeptide α2L (15 residues; α2 with one additional leucine residue on its carboxyl terminal) did form an α-helix and fibrous assembly. Fibrous assembly formation was associated with polypeptides at least as long as polypeptide α2L and with five leucine residues, indicating that the C-terminal leucine has a critical element for stabilization of α-helix and fibril formation. In contrast, polypeptides α5 (35 residues) and α6 (42 residues) aggregated easily, although they formed α-helices. A 15-35-residue chain was required for fibrous assembly formation. Electron microscopy and X-ray fiber diffraction showed that the thinnest fibrous assemblies of polypeptides were about 20 Å and had periodicities coincident with the length of the α-helix in a longitudinal direction. These results indicated that the α-helix structures were orientated along the fibrous axis and assembled into a bundle. Furthermore, the width and length of fibrous assemblies changed with changes in the pH value, resulting in variations in the charged states of the residues. Our results suggest that the formation of fibrous assemblies of amphipathic α-helices is due to the assembly of bundles via the hydrophobic faces of the helices and extension with hydrophobic noncovalent bonds containing a leucine.

Original languageEnglish
Pages (from-to)2810-2820
Number of pages11
JournalBiochemistry
Volume52
Issue number16
DOIs
Publication statusPublished - 2013 Apr 23
Externally publishedYes

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Chain length
Amino Acid Sequence
Amino Acids
Peptides
Leucine
Periodicity
X-Ray Diffraction
Electron Microscopy
Electron microscopy
Stabilization
Diffraction
X rays
Fibers

ASJC Scopus subject areas

  • Biochemistry

Cite this

Effects of chain length of an amphipathic polypeptide carrying the repeated amino acid sequence (LETLAKA)n on α-helix and fibrous assembly formation. / Takei, Toshiaki; Hasegawa, Kazuya; Imada, Katsumi; Namba, Keiichi; Tsumoto, Kouhei; Kuriki, Yukino; Yoshino, Masakuni; Yazaki, Kazumori; Kojima, Shuichi; Takei, Tsunetomo; Ueda, Takuya; Miura, Kin Ichiro.

In: Biochemistry, Vol. 52, No. 16, 23.04.2013, p. 2810-2820.

Research output: Contribution to journalArticle

Takei, T, Hasegawa, K, Imada, K, Namba, K, Tsumoto, K, Kuriki, Y, Yoshino, M, Yazaki, K, Kojima, S, Takei, T, Ueda, T & Miura, KI 2013, 'Effects of chain length of an amphipathic polypeptide carrying the repeated amino acid sequence (LETLAKA)n on α-helix and fibrous assembly formation', Biochemistry, vol. 52, no. 16, pp. 2810-2820. https://doi.org/10.1021/bi400001c
Takei, Toshiaki ; Hasegawa, Kazuya ; Imada, Katsumi ; Namba, Keiichi ; Tsumoto, Kouhei ; Kuriki, Yukino ; Yoshino, Masakuni ; Yazaki, Kazumori ; Kojima, Shuichi ; Takei, Tsunetomo ; Ueda, Takuya ; Miura, Kin Ichiro. / Effects of chain length of an amphipathic polypeptide carrying the repeated amino acid sequence (LETLAKA)n on α-helix and fibrous assembly formation. In: Biochemistry. 2013 ; Vol. 52, No. 16. pp. 2810-2820.
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abstract = "Polypeptide α3 (21 residues), with three repeats of a seven-amino-acid sequence (LETLAKA)3, forms an amphipathic α-helix and a long fibrous assembly. Here, we investigated the ability of α3-series polypeptides (with 14-42 residues) of various chain lengths to form α-helices and fibrous assemblies. Polypeptide α2 (14 residues), with two same-sequence repeats, did not form an α-helix, but polypeptide α2L (15 residues; α2 with one additional leucine residue on its carboxyl terminal) did form an α-helix and fibrous assembly. Fibrous assembly formation was associated with polypeptides at least as long as polypeptide α2L and with five leucine residues, indicating that the C-terminal leucine has a critical element for stabilization of α-helix and fibril formation. In contrast, polypeptides α5 (35 residues) and α6 (42 residues) aggregated easily, although they formed α-helices. A 15-35-residue chain was required for fibrous assembly formation. Electron microscopy and X-ray fiber diffraction showed that the thinnest fibrous assemblies of polypeptides were about 20 {\AA} and had periodicities coincident with the length of the α-helix in a longitudinal direction. These results indicated that the α-helix structures were orientated along the fibrous axis and assembled into a bundle. Furthermore, the width and length of fibrous assemblies changed with changes in the pH value, resulting in variations in the charged states of the residues. Our results suggest that the formation of fibrous assemblies of amphipathic α-helices is due to the assembly of bundles via the hydrophobic faces of the helices and extension with hydrophobic noncovalent bonds containing a leucine.",
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AU - Takei, Toshiaki

AU - Hasegawa, Kazuya

AU - Imada, Katsumi

AU - Namba, Keiichi

AU - Tsumoto, Kouhei

AU - Kuriki, Yukino

AU - Yoshino, Masakuni

AU - Yazaki, Kazumori

AU - Kojima, Shuichi

AU - Takei, Tsunetomo

AU - Ueda, Takuya

AU - Miura, Kin Ichiro

PY - 2013/4/23

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N2 - Polypeptide α3 (21 residues), with three repeats of a seven-amino-acid sequence (LETLAKA)3, forms an amphipathic α-helix and a long fibrous assembly. Here, we investigated the ability of α3-series polypeptides (with 14-42 residues) of various chain lengths to form α-helices and fibrous assemblies. Polypeptide α2 (14 residues), with two same-sequence repeats, did not form an α-helix, but polypeptide α2L (15 residues; α2 with one additional leucine residue on its carboxyl terminal) did form an α-helix and fibrous assembly. Fibrous assembly formation was associated with polypeptides at least as long as polypeptide α2L and with five leucine residues, indicating that the C-terminal leucine has a critical element for stabilization of α-helix and fibril formation. In contrast, polypeptides α5 (35 residues) and α6 (42 residues) aggregated easily, although they formed α-helices. A 15-35-residue chain was required for fibrous assembly formation. Electron microscopy and X-ray fiber diffraction showed that the thinnest fibrous assemblies of polypeptides were about 20 Å and had periodicities coincident with the length of the α-helix in a longitudinal direction. These results indicated that the α-helix structures were orientated along the fibrous axis and assembled into a bundle. Furthermore, the width and length of fibrous assemblies changed with changes in the pH value, resulting in variations in the charged states of the residues. Our results suggest that the formation of fibrous assemblies of amphipathic α-helices is due to the assembly of bundles via the hydrophobic faces of the helices and extension with hydrophobic noncovalent bonds containing a leucine.

AB - Polypeptide α3 (21 residues), with three repeats of a seven-amino-acid sequence (LETLAKA)3, forms an amphipathic α-helix and a long fibrous assembly. Here, we investigated the ability of α3-series polypeptides (with 14-42 residues) of various chain lengths to form α-helices and fibrous assemblies. Polypeptide α2 (14 residues), with two same-sequence repeats, did not form an α-helix, but polypeptide α2L (15 residues; α2 with one additional leucine residue on its carboxyl terminal) did form an α-helix and fibrous assembly. Fibrous assembly formation was associated with polypeptides at least as long as polypeptide α2L and with five leucine residues, indicating that the C-terminal leucine has a critical element for stabilization of α-helix and fibril formation. In contrast, polypeptides α5 (35 residues) and α6 (42 residues) aggregated easily, although they formed α-helices. A 15-35-residue chain was required for fibrous assembly formation. Electron microscopy and X-ray fiber diffraction showed that the thinnest fibrous assemblies of polypeptides were about 20 Å and had periodicities coincident with the length of the α-helix in a longitudinal direction. These results indicated that the α-helix structures were orientated along the fibrous axis and assembled into a bundle. Furthermore, the width and length of fibrous assemblies changed with changes in the pH value, resulting in variations in the charged states of the residues. Our results suggest that the formation of fibrous assemblies of amphipathic α-helices is due to the assembly of bundles via the hydrophobic faces of the helices and extension with hydrophobic noncovalent bonds containing a leucine.

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