Reversible Heat-Induced Dissociation of 尾2-Microglobulin Amyloid Fibrils

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• 作者：Jo虂zsef Kardos ; Andra虂s Micsonai ; Henriett Pa虂l-Ga虂bor ; E虂va Petrik ; La虂szlo虂 Gra虂f ; Ja虂nos Kova虂cs ; Young-Ho Lee ; Hironobu Naiki ; Yuji Goto
• 刊名：Biochemistry
• 出版年：2011
• 出版时间：April 19, 2011
• 年：2011
• 卷：50
• 期：15
• 页码：3211-3220
• 全文大小：922K
• 年卷期：v.50,no.15(April 19, 2011)
• ISSN：1520-4995

文摘

Recent progress in the field of amyloid research indicates that the classical view of amyloid fibrils, being irreversibly formed highly stable structures resistant to perturbating conditions and proteolytic digestion, is getting more complex. We studied the thermal stability and heat-induced depolymerization of amyloid fibrils of 尾₂-microglobulin (尾2m), a protein responsible for dialysis-related amyloidosis. We found that freshly polymerized 尾2m fibrils at 0.1鈭?.3 mg/mL concentration completely dissociated to monomers upon 10 min incubation at 99 掳C. Fibril depolymerization was followed by thioflavin-T fluorescence and circular dichroism spectroscopy at various temperatures. Dissociation of 尾2m fibrils was found to be a reversible and dynamic process reaching equilibrium between fibrils and monomers within minutes. Repolymerization experiments revealed that the number of extendable fibril ends increased significantly upon incubation at elevated temperatures suggesting that the mechanism of fibril unfolding involves two distinct processes: (1) dissociation of monomers from the fibril ends and (2) the breakage of fibrils. The breakage of fibrils may be an important in vivo factor multiplying the number of fibril nuclei and thus affecting the onset and progress of disease. We investigated the effects of some additives and different factors on the stability of amyloid fibrils. Sample aging increased the thermal stability of 尾2m fibril solution. 0.5 mM SDS completely prevented 尾2m fibrils from dissociation up to the applied highest temperature of 99 掳C. The generality of our findings was proved on fibrils of K3 peptide and 伪-synuclein. Our simple method may also be beneficial for screening and developing amyloid-active compounds for therapeutic purposes.