Abstract
Vps4p and Vps36p of Saccharomyces cerevisiae are involved in the transport of proteins to the vacuole via the carboxypeptidase Y pathway. We found that deletion of VPS4 and VPS36 caused impaired maturation of the vacuolar proaminopeptidase I (pAPI) via autophagy or the cytosol to vacuole targeting pathway. Supplementation with ethanolamine rescued this defect, leading to an increase of the cellular amount of phosphatidylethanolamine (PtdEtn), an enhanced level of the PtdEtn-binding autophagy protein Atg8p and a balanced rate of autophagy. We also discovered that maturation of pAPI was generally affected by PtdEtn depletion in a psd1Delta psd2Delta mutant due to reduced recruitment of Atg8p to the preautophagosomal structure. Ethanolamine supplementation provided the necessary amounts of PtdEtn for complete maturation of pAPI. Since the expression level of Atg8p was not compromised in the psd1Delta psd2Delta strain, we concluded that the amount of available PtdEtn was limiting. Thus, PtdEtn appears to be a limiting factor for the balance of the carboxypeptidase Y pathway and autophagy/the cytosol to vacuole targeting pathway in the yeast.
Highlights
Depletion of PtdEtn causes defects in the assembly of mitochondrial protein complexes and loss of mitochondrial DNA (1, 3, 4)
A Screen for Mutants with an Enhanced Requirement for Phosphatidylethanolamine Identifies vps4 and vps36—To investigate the function of PtdEtn in yeast cells and to identify processes that depend on PtdEtn, we performed a screening for mutants that require exogenous ethanolamine as a supplement when cellular PtdEtn homeostasis is disturbed
We present a screening for additional gene products with a specific requirement for PtdEtn, which identified VPS4 and VPS36
Summary
Tion of a class E VPS gene, does not lead to a complete Analysis of Strains Bearing a GFP-Atg8p Hybrid—Cells block in protein and membrane transport to the vacuole. In this expressing the centromeric plasmid GFP-Atg8p, which carries case, translocation of polypeptides may occur by alternative a GFP-Atg8p fusion under the native Atg8p promoter We demonstrate that full activity of the latter route grown to the late logarithmic growth phase on SL medium suprequires a certain cellular level of PtdEtn, which is essential for plemented with Etn and shifted to SL(ϪN) supplemented with the formation of autophagosomes/Cvt vesicles by covalently Etn for 4 h. The general requirement for PtdEtn in the scope, and cells with fluorescence signals on the PAS were targeting of proteins to the vacuole is discussed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
