Endoplasmic Reticulum-Associated Degradation of mutated forms of yeast ABC-transporter Pdr5
(2011)
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- Authors
- Supervisors
- Ghislain , Michel
- Abstract
- (en) One of the research activity in our laboratory focuses on the quality control and degradation of mutated versions of the yeast plasma membrane ABC-transporter Pdr5. The main objective of the doctoral work was to ascertain the veracity of the ERAD model established with engineered fusion proteins featuring how newly synthesized membrane proteins are targeted for degradation by the proteasome. Depending of the localization of the mutated domain, ER lumen versus the cytosol, the ERAD model predicts that misfolded proteins are degraded via different pathways (Carvalho et al. 2006; Vashist et al. 2001; Vashist and Ng 2004). To ascertain the model, we have contructed 3 protein variants, Pdr5L183P, Pdr5C1427Y and Pdr5L183P+C1427Y. According to the model, Pdr5L183P that is misfolded as the result of a mutation in a cytosolic region should be ubiquitylated by the Ub-ligase Doa10p (ERAD-C pathway) and transported back to the cytosol in a Der1p and Sec61p-independent process. In contrast, Pdr5C1427Y with a misfolded region facing the ER lumen should be ubiquitylated by Hrd1p (ERAD-L pathway) and required Der1p and/or Sec61p for its degradation. Pdr5L183P+C1427Y variant that combines the cytosolic and luminal substitutions should be targeted by the ERAD-C pathway for degradation as this pathway predominates the ERAD-L pathway. The importance of the ER-to-Golgi transport (post-ER quality control) for proteasome-mediated degradation of mutated variants have been also tested. An other objective of this work is the identification of amino-acid determinants in the Pdr5 sequence which trigger the quality control system and subsequent degradation using C-truncated variants.
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Citations
Campagnolo, N. (2011). Endoplasmic Reticulum-Associated Degradation of mutated forms of yeast ABC-transporter Pdr5. https://hdl.handle.net/2078.5/155808