Limits...
Effect of reparation of repeat sequences in the human alpha-synuclein on fibrillation ability.

Sode K, Ochiai S, Kobayashi N, Usuzaka E - Int. J. Biol. Sci. (2006)

Bottom Line: The hexamer motif KTKEGV is found in each of the seven imperfect repeat sequences in the N-terminal half of alpha-synuclein.Resistance to formation in the partially folded intermediate may repress the folding of alpha-synuclein, consequently interfering with the aggregation and fibril formation.These results demonstrated that KTKEGV repeats may have a significant role in keeping native unfolded status of alpha-synuclein.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, Graduate School of Engineering, Tokyo University of Agriculture & Technology, 2-2-4-16, Nakacho, Koganei, Tokyo 184-8588, Japan. sode@cc.tuat.ac.jp

ABSTRACT
The aggregation and fibrillation of alpha-synuclein has been implicated as a causative factor in the Parkinson's disease. The hexamer motif KTKEGV is found in each of the seven imperfect repeat sequences in the N-terminal half of alpha-synuclein. The motif is not fully conserved in the sixth and seventh repeats. We created mutants in which the motif was repaired to be fully conserved in either (Rep6 and Rep7) or both (Rep67) of these two repeats. The Rep6 and Rep67 mutants showed a greatly reduced propensity to aggregate and fibrillate while all three mutants showed greater resistance to HFIP-induced formation of the alpha-helix intermediate. Resistance to formation in the partially folded intermediate may repress the folding of alpha-synuclein, consequently interfering with the aggregation and fibril formation. These results demonstrated that KTKEGV repeats may have a significant role in keeping native unfolded status of alpha-synuclein.

Show MeSH

Related in: MedlinePlus

α-Synuclein mutants introduced amino acid substitution into the incomplete repeat sequences in NAC region. The boxed regions indicate incomplete repeat regions. Red letters indicate conserved amino acids in the characteristic hexamer motif (KTKEGV). Green letters represent the mutated residues.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC1622890&req=5

Figure 1: α-Synuclein mutants introduced amino acid substitution into the incomplete repeat sequences in NAC region. The boxed regions indicate incomplete repeat regions. Red letters indicate conserved amino acids in the characteristic hexamer motif (KTKEGV). Green letters represent the mutated residues.

Mentions: However, none has ever reported on the role of KTKEGV repeated sequence in α-synuclein structure, particularly in the protein folded process and/or keeping its random structure. The lack in the information about the role of this one of the characteristic primary sequence in α-synuclein, KTKEGV, inspired us to initiate the reparation of imperfect sequence in this molecule. Interestingly, among the seven 11-amino acid imperfect repeats, the characteristic hexameric motifs in the two repeats located within the NAC region are not conserved (Figure 1). In order to investigate the role of these two non-conserved hexameric motifs on the aggregation and fibril formation ability of α-synuclein, we carried out a site-directed mutagenesis study on this region. We constructed three mutant α-synucleins in which either or both of the nonconserved hexameric motifs in the 6th and 7th repeats were substituted to the conserved KTKEGV sequence (Figure 1). We investigated the propensity of the mutant α-synucleins to form fibrils and aggregates, as well as their propensity to form α-helices. Our findings suggest that the two 11-residue repeat sequences in the NAC region have a strong effect on α-synuclein folding and the 6th repeat sequence has a particularly strong influence on α-synuclein's propensity to aggregate and fibrillate.


Effect of reparation of repeat sequences in the human alpha-synuclein on fibrillation ability.

Sode K, Ochiai S, Kobayashi N, Usuzaka E - Int. J. Biol. Sci. (2006)

α-Synuclein mutants introduced amino acid substitution into the incomplete repeat sequences in NAC region. The boxed regions indicate incomplete repeat regions. Red letters indicate conserved amino acids in the characteristic hexamer motif (KTKEGV). Green letters represent the mutated residues.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1622890&req=5

Figure 1: α-Synuclein mutants introduced amino acid substitution into the incomplete repeat sequences in NAC region. The boxed regions indicate incomplete repeat regions. Red letters indicate conserved amino acids in the characteristic hexamer motif (KTKEGV). Green letters represent the mutated residues.
Mentions: However, none has ever reported on the role of KTKEGV repeated sequence in α-synuclein structure, particularly in the protein folded process and/or keeping its random structure. The lack in the information about the role of this one of the characteristic primary sequence in α-synuclein, KTKEGV, inspired us to initiate the reparation of imperfect sequence in this molecule. Interestingly, among the seven 11-amino acid imperfect repeats, the characteristic hexameric motifs in the two repeats located within the NAC region are not conserved (Figure 1). In order to investigate the role of these two non-conserved hexameric motifs on the aggregation and fibril formation ability of α-synuclein, we carried out a site-directed mutagenesis study on this region. We constructed three mutant α-synucleins in which either or both of the nonconserved hexameric motifs in the 6th and 7th repeats were substituted to the conserved KTKEGV sequence (Figure 1). We investigated the propensity of the mutant α-synucleins to form fibrils and aggregates, as well as their propensity to form α-helices. Our findings suggest that the two 11-residue repeat sequences in the NAC region have a strong effect on α-synuclein folding and the 6th repeat sequence has a particularly strong influence on α-synuclein's propensity to aggregate and fibrillate.

Bottom Line: The hexamer motif KTKEGV is found in each of the seven imperfect repeat sequences in the N-terminal half of alpha-synuclein.Resistance to formation in the partially folded intermediate may repress the folding of alpha-synuclein, consequently interfering with the aggregation and fibril formation.These results demonstrated that KTKEGV repeats may have a significant role in keeping native unfolded status of alpha-synuclein.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, Graduate School of Engineering, Tokyo University of Agriculture & Technology, 2-2-4-16, Nakacho, Koganei, Tokyo 184-8588, Japan. sode@cc.tuat.ac.jp

ABSTRACT
The aggregation and fibrillation of alpha-synuclein has been implicated as a causative factor in the Parkinson's disease. The hexamer motif KTKEGV is found in each of the seven imperfect repeat sequences in the N-terminal half of alpha-synuclein. The motif is not fully conserved in the sixth and seventh repeats. We created mutants in which the motif was repaired to be fully conserved in either (Rep6 and Rep7) or both (Rep67) of these two repeats. The Rep6 and Rep67 mutants showed a greatly reduced propensity to aggregate and fibrillate while all three mutants showed greater resistance to HFIP-induced formation of the alpha-helix intermediate. Resistance to formation in the partially folded intermediate may repress the folding of alpha-synuclein, consequently interfering with the aggregation and fibril formation. These results demonstrated that KTKEGV repeats may have a significant role in keeping native unfolded status of alpha-synuclein.

Show MeSH
Related in: MedlinePlus