Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Heparin promotes the rapid fibrillization of a peptide with low intrinsic amyloidogenicity
AU - Madine, Jidlian
AU - Davies, Hannah A.
AU - Hughes, Eleri
AU - Middleton, David A.
PY - 2013/12/17
Y1 - 2013/12/17
N2 - Amyloid deposits in vivo are complex mixtures composed of protein fibrils and nonfibrillar components, including polysaccharides of the glycosaminoglycan (GAG) class. It has been widely documented that GAGs influence the initiation and progress of self-assembly by several disease-associated amyloidogenic proteins and peptides in vitro. Here we investigated whether the GAG heparin can serve as a cofactor to induce amyloid-like fibril formation in a peptide predicted to have a weak propensity to aggregate and not associated with amyloid disorders. We selected the 23-residue peptide PLB(1-23), which corresponds to the acetylated cytoplasmic domain of the phospholamban transmembrane protein. PLB(1-23) remains unfolded in aqueous solution for > 24 h and does not bind thioflavin T over this time period, in agreement with computer predictions that the peptide has a very low intrinsic amyloidogenicity. In the presence of low-molecular mass (S kDa) heparin, which binds PLB(1-23) with micromolar affinity, the peptide undergoes spontaneous and rapid assembly into amyloid-like fibrils, the effect being more pronounced at pH 5.5 than at pH 7.4. At the lower pH, peptide aggregation is accompanied by a transition to a beta-sheet rich structure. These results are consistent with the polyanionic heparin serving as a scaffold to enhance aggregation by aligning the peptide molecules in the correct orientation and with the appropriate periodicity. PLB(1-23) is toxic to cells when added in isolation, and promotion of fibril formation by heparin can reduce the toxicity of this peptide, consistent with the notion that amyloid-like fibrils represent a benign end stage of fibrillization. This work provides insight into the role that heparin and other glycosaminoglycans may play in amyloid formation and provides therapeutic avenues targeting the reduction of cytotoxicity of species along the amyloid formation pathway.
AB - Amyloid deposits in vivo are complex mixtures composed of protein fibrils and nonfibrillar components, including polysaccharides of the glycosaminoglycan (GAG) class. It has been widely documented that GAGs influence the initiation and progress of self-assembly by several disease-associated amyloidogenic proteins and peptides in vitro. Here we investigated whether the GAG heparin can serve as a cofactor to induce amyloid-like fibril formation in a peptide predicted to have a weak propensity to aggregate and not associated with amyloid disorders. We selected the 23-residue peptide PLB(1-23), which corresponds to the acetylated cytoplasmic domain of the phospholamban transmembrane protein. PLB(1-23) remains unfolded in aqueous solution for > 24 h and does not bind thioflavin T over this time period, in agreement with computer predictions that the peptide has a very low intrinsic amyloidogenicity. In the presence of low-molecular mass (S kDa) heparin, which binds PLB(1-23) with micromolar affinity, the peptide undergoes spontaneous and rapid assembly into amyloid-like fibrils, the effect being more pronounced at pH 5.5 than at pH 7.4. At the lower pH, peptide aggregation is accompanied by a transition to a beta-sheet rich structure. These results are consistent with the polyanionic heparin serving as a scaffold to enhance aggregation by aligning the peptide molecules in the correct orientation and with the appropriate periodicity. PLB(1-23) is toxic to cells when added in isolation, and promotion of fibril formation by heparin can reduce the toxicity of this peptide, consistent with the notion that amyloid-like fibrils represent a benign end stage of fibrillization. This work provides insight into the role that heparin and other glycosaminoglycans may play in amyloid formation and provides therapeutic avenues targeting the reduction of cytotoxicity of species along the amyloid formation pathway.
KW - AMYLOID FIBRIL FORMATION
KW - FORMATION IN-VITRO
KW - GLYCOSAMINOGLYCAN INTERACTIONS
KW - PROTEIN AGGREGATION
KW - BETA-AGGREGATION
KW - PRION PROTEIN
KW - DISEASE
KW - BINDING
KW - LIGHT
KW - BETA(2)-MICROGLOBULIN
U2 - 10.1021/bi401231u
DO - 10.1021/bi401231u
M3 - Journal article
VL - 52
SP - 8984
EP - 8992
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 50
ER -