Supersaturation-limited and unlimited phase transitions compete to produce the pathway complexity in amyloid fibrillation

Masayuki Adachi, Masatomo So, Kazumasa Sakurai, József Kardos, Yuji Goto

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Although amyloid fibrils and amorphous aggregates are two types of aggregates formed by denatured proteins, their relationship currently remains unclear. We used β2-microglobulin (β2m), a protein responsible for dialysis-related amyloidosis, to clarify the mechanism by which proteins form either amyloid fibrils or amorphous aggregates.Whenultrasonication was used to accelerate the spontaneous fibrillation of β2m at pH 2.0, the effects observed depended on ultrasonic power; although stronger ultrasonic power effectively accelerated fibrillation, excessively strong ultrasonic power decreased the amount of fibrils formed, as monitored by thioflavin T fluorescence. An analysis of the products formed indicated that excessively strong ultrasonic power generated fibrillar aggregates that retained β-structures but without high efficiency as seeds. On the other hand, when the spontaneous fibrillation of β2m was induced at higher concentrations of NaCl at pH 2.0 with stirring, amorphous aggregates became more dominant than amyloid fibrils. These apparent complexities in fibrillation were explained comprehensively by a competitive mechanism in which supersaturation- limited reactions competed with supersaturation-unlimited reactions. We link the kinetics of protein aggregation and a conformational phase diagram, in which supersaturation played important roles.

Original languageEnglish
Pages (from-to)18134-18145
Number of pages12
JournalJournal of Biological Chemistry
Volume290
Issue number29
DOIs
Publication statusPublished - Jul 17 2015

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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