Fig. 3.

Plasmid overexpression screen identifies ER-Golgi trafficking genes as modifiers of αSyn toxicity. (A) Representative plates from αSyn modifier screen (24). αSyn-expressing cells were transformed individually with each of 3000 random ORFs under the control of a galactose-inducible promoter. Transformants were grown on synthetic media containing either glucose (control, αSyn ‘‘off’’) or galactose (to induce expression of αSyn and candidate ORFs, αSyn ‘‘on’’). Examples of strong- and moderate-toxicity suppressors are shown as black and blue circles, respectively. Examples of enhancers of αSyn-induced toxicity are shown as red circles, and a false-positive that did not reproduce upon further analysis is shown as a yellow circle. (B) Spotting assay shows that overexpression of ER-Golgi trafficking genes YPT1, YKT6, BRE5, UBP3, and ERV29 suppress αSyn-induced toxicity, whereas GYP8 and PMR1 overexpression enhances toxicity. (C) Suppression of toxicity is specific to the transport step facilitated by YPT1, because overexpression of other Rab GTPases has no effect on growth.