Abstract: The aggregation of alpha-synuclein (α-SYN) into fibrils is characteristic for several neurodegenerative diseases, including Parkinson’s disease (PD). Ninety percent of α-SYN deposited in Lewy Bodies, a pathological hallmark of PD, is phosphorylated on serine129. α-SYN can also be phosphorylated on tyrosine125, which is believed to regulate the membrane binding capacity and thus possibly its normal function. A better understanding of the effect of phosphorylation on the aggregation of α-SYN might shed light on its role in the pathogenesis of PD. In this study we compare the aggregation properties of WT α-SYN with the phospho-dead and phospho-mimic mutants S129A, S129D, Y125F and Y125E and in vitro phosphorylated α-SYN using turbidity, thioflavin T and circular dichroism measurements as well as transmission electron microscopy. We show that the mutants S129A and S129D behave similarly compared to wild type (WT) α-SYN, while the mutants Y125F and Y125E fibrillate significantly slower, although all mutants form fibrillar structures similar to the WT protein. In contrast, in vitro phosphorylation of α-SYN on either S129 or Y125 does not significantly affect the fibrillization kinetics. Moreover, FK506 binding proteins (FKBPs), enzymes with peptidyl-prolyl cis-trans isomerase activity, still accelerate the aggregation of phosphorylated α-SYN in vitro, as was shown previously for WT α-SYN. In conclusion, our results illustrate that phosphorylation mutants can display different aggregation properties compared to the more biologically relevant phosphorylated form of α-SYN.
Keywords: alpha-synuclein; phosphorylation; parkinson’s disease; phosphorylation mutants; FKBP; in vitro fibrillization
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Schreurs, S.; Gerard, M.; Derua, R.; Waelkens, E.; Taymans, J.-M.; Baekelandt, V.; Engelborghs, Y. In Vitro Phosphorylation Does not Influence the Aggregation Kinetics of WT α-Synuclein in Contrast to Its Phosphorylation Mutants. Int. J. Mol. Sci. 2014, 15, 1040-1067.
Schreurs S, Gerard M, Derua R, Waelkens E, Taymans J-M, Baekelandt V, Engelborghs Y. In Vitro Phosphorylation Does not Influence the Aggregation Kinetics of WT α-Synuclein in Contrast to Its Phosphorylation Mutants. International Journal of Molecular Sciences. 2014; 15(1):1040-1067.
Schreurs, Sarah; Gerard, Melanie; Derua, Rita; Waelkens, Etienne; Taymans, Jean-Marc; Baekelandt, Veerle; Engelborghs, Yves. 2014. "In Vitro Phosphorylation Does not Influence the Aggregation Kinetics of WT α-Synuclein in Contrast to Its Phosphorylation Mutants." Int. J. Mol. Sci. 15, no. 1: 1040-1067.