科研之友
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摘要
The presynaptic protein alpha-synuclein (alpha-syn), particularly in its amyloid form, is widely recognized for its involvement in Parkinson disease (PD). Recent genetic studies reveal that mutations in the gene GBA are the most widespread genetic risk factor for parkinsonism identified to date. GBA encodes for glucocerebrosidase (GCase), the enzyme deficient in the lysosomal storage disorder, Gaucher disease (GD). In this work, we investigated the possibility of a physical linkage between alpha-syn and GCase, examining both wild type and the GD-related N370S mutant enzyme. Using fluorescence and nuclear magnetic resonance spectroscopy, we determined that alpha-syn and GCase interact selectively under lysosomal solution conditions (pH 5.5) and mapped the interaction site to the alpha-syn C-terminal residues, 118-137. This alpha-syn-GCase complex does not form at pH 7.4 and is stabilized by electrostatics, with dissociation constants ranging from 1.2 to 22 mu M in the presence of 25 to 100mM NaCl. Intriguingly, the N370S mutant form of GCase has a reduced affinity for alpha-syn, as does the inhibitor conduritol-beta-epoxidebound enzyme. Immunoprecipitation and immunofluorescence studies verified this interaction in human tissue and neuronal cell culture, respectively. Although our data do not preclude protein-protein interactions in other cellular milieux, we suggest that the alpha-syn-GCase association is favored in the lysosome, and that this noncovalent interaction provides the groundwork to explore molecular mechanisms linking PD with mutant GBA alleles.
- 出版日期2011-8-12
