Characterization of semisynthetic and naturally Nα-acetylated α-synuclein in vitro and in intact cells: implications for aggregation and cellular properties of α-synuclein.
N-terminal acetylation is a very common post-translational modification, although its role in regulating protein physical properties and function remains poorly understood. α-Synuclein (α-syn), a protein that has been linked to the pathogenesis of Parkinson disease, is constitutively N(α)-acetylated in vivo. Nevertheless, most of the biochemical and biophysical studies on the structure, aggregation, and function of α-syn in vitro utilize recombinant α-syn from Escherichia coli, which is not N-terminally acetylated. To elucidate the effect of N(α)-acetylation on the biophysical and biological properties of α-syn, we produced N(α)-acetylated α-syn first using a semisynthetic methodology based on expressed protein ligation (Berrade, L., and Camarero, J. A. (2009) Cell. Mol. Life Sci. 66, 3909-3922) and then a recombinant expression strategy, to compare its properties to unacetylated α-syn. We demonstrate that both WT and N(α)-acetylated α-syn share a similar secondary structure and oligomeric state using both purified protein preparations and in-cell NMR on E. coli overexpressing N(α)-acetylated α-syn. The two proteins have very close aggregation propensities as shown by thioflavin T binding and sedimentation assays. Furthermore, both N(α)-acetylated and WT α-syn exhibited similar ability to bind synaptosomal membranes in vitro and in HeLa cells, where both internalized proteins exhibited prominent cytosolic subcellular distribution. We then determined the effect of attenuating N(α)-acetylation in living cells, first by using a nonacetylable mutant and then by silencing the enzyme responsible for α-syn N(α)-acetylation. Both approaches revealed similar subcellular distribution and membrane binding for both the nonacetylable mutant and WT α-syn, suggesting that N-terminal acetylation does not significantly affect its structure in vitro and in intact cells.
Laboratory of Molecular and Chemical Biology of Neurodegeneration, Station 19, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
Bruno
B
Fauvet
Mohamed-Bilal
MB
Fares
Filsy
F
Samuel
Igor
I
Dikiy
Anurag
A
Tandon
David
D
Eliezer
Hilal A
HA
Lashuel
D000107:Acetylation; D000818:Animals; D052160:Benzothiazoles; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010300:Parkinson Disease / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae; D013844:Thiazoles / Q000737:chemistry; D051844:alpha-Synuclein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D052160:Benzothiazoles; D046912:Multiprotein Complexes; D013844:Thiazoles; D051844:alpha-Synuclein; C009462:thioflavin T