Post date: Jul 13, 2015 4:27:49 PM

J Biol Chem. 2015 Jul 7. pii: jbc.M115.662312.

A two-step protein quality control pathway for a misfolded DJ-1 variant in fission yeast.

Mathiassen SG, Larsen IB, Poulsen EG, Madsen CT, Papaleo E, Lindorff-Larsen K, Kragelund BB, Nielsen ML, Kriegenburg F, Hartmann-Petersen R.

A mutation, L166P, in the cytosolic protein, PARK7/DJ-1, causes protein misfolding and is linked to Parkinson's disease. Here, we identify the fission yeast protein Sdj1 as the orthologue of DJ-1 and calculate by in silico saturation mutagenesis the effects of point mutants on its structural stability. We also map the degradation pathways for Sdj1-L169P, the fission yeast orthologue of the disease-causing DJ-1 L166P protein. Sdj1-L169P forms inclusions, which are enriched for the Hsp104 disaggregase. Hsp104 and Hsp70-type chaperones are required for efficient degradation of Sdj1-L169P. This also depends on the ribosome-associated E3 ligase Ltn1 and its co-factor Rqc1. While Hsp104 is absolutely required for proteasomal degradation of Sdj1-L169P aggregates, the degradation of already aggregated Sdj1-L169P occurs independently of Ltn1 and Rqc1. Thus, our data point to soluble Sdj1-L169P being targeted early by Ltn1 and Rqc1. The fraction of Sdj1-L169P that escapes this first inspection then forms aggregates that are subsequently cleared via an Hsp104- and proteasome-dependent pathway.

http://www.ncbi.nlm.nih.gov/pubmed/26152728