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Glycation modulates alpha-synuclein fibrillization kinetics: a sweet spot for inhibition

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  • Azad Farzadfard, University of Tehran
  • ,
  • Annekatrin König, University Medical Center Göttingen
  • ,
  • Steen Vang Petersen
  • Janni Nielsen
  • Eftychia Vasili, University Medical Center Göttingen
  • ,
  • Antonio Dominguez-Meijide, University Medical Center Göttingen
  • ,
  • Alexander K Buell, Technical University of Denmark
  • ,
  • Tiago Fleming Outeiro, Newcastle University
  • ,
  • Daniel E Otzen

Glycation is a non-enzymatic posttranslational modification (PTM) known to be increased in the brains of hyperglycemic patients. α-synuclein (αSN), a central player in the etiology of Parkinson's disease (PD), can be glycated at lysine residues, thereby reducing αSN fibril formation in vitro and modulating αSN aggregation in cells. However, the molecular basis for these effects is unclear. To elucidate this, we investigated the aggregation of αSN modified by eight glycating agents, namely the dicarbonyl compound methylglyoxal (MGO) and the sugars ribose, fructose, mannose, glucose, galactose, sucrose, and lactose. We found that MGO and ribose modify αSN to the greatest extent, and these glycation products are the most efficient inhibitors of fibril formation. We show glycation primarily inhibits elongation rather than nucleation of αSN, and has only a modest effect on the level of oligomerization. Furthermore, glycated αSN is not significantly incorporated into fibrils. For both MGO and ribose, we discovered that a level of ∼5 modifications per αSN is optimal for inhibition of elongation. The remaining sugars showed a weak but optimal inhibition at ∼2 modifications per αSN. We propose that this optimal level balances the affinity for the growing ends of the fibril (which decreases with the extent of modification) with the ability to block incorporation of subsequent αSN subunits (which increases with modification). Our results are not only relevant for other αSN PTMs, but also for understanding PTMs affecting other fibrillogenic proteins, and may thus open novel avenues for therapeutic intervention in protein aggregation disorders.

Original languageEnglish
Article number101848
JournalThe Journal of Biological Chemistry
Volume298
Issue5
Number of pages14
ISSN0021-9258
DOIs
Publication statusPublished - May 2022

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