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J Mol Biol. 2007 Mar 9;366(5):1510-22. Epub 2006 Dec 21.

Relationships between the sequence of alpha-synuclein and its membrane affinity, fibrillization propensity, and yeast toxicity.

Author information

1
Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Cambridge, MA 02139, USA.

Abstract

To investigate the alpha-synuclein protein and its role in Parkinson's disease, we screened a library of random point mutants both in vitro and in yeast to find variants in an unbiased way that could help us understand the sequence-phenotype relationship. We developed a rapid purification method that allowed us to screen 59 synuclein mutants in vitro and discovered two double-point mutants that fibrillized slowly relative to wild-type, A30P, and A53T alpha-synucleins. The yeast toxicity of all of these proteins was measured, and we found no correlation with fibrillization rate, suggesting that fibrillization is not necessary for synuclein-induced yeast toxicity. We found that beta-synuclein was of intermediate toxicity to yeast, and gamma-synuclein was non-toxic. Co-expression of Parkinson's disease-related genes DJ-1, parkin, Pink1, UCH-L1, or synphilin, with synuclein, did not affect synuclein toxicity. A second screen, of several thousand library clones in yeast, identified 25 non-toxic alpha-synuclein sequence variants. Most of these contained a mutation to either proline or glutamic acid that caused a defect in membrane binding. We hypothesize that yeast toxicity is caused by synuclein binding directly to membranes at levels sufficient to non-specifically disrupt homeostasis.

PMID:
17222866
PMCID:
PMC1868670
DOI:
10.1016/j.jmb.2006.12.044
[Indexed for MEDLINE]
Free PMC Article

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