Efficient degradation of misfolded mutant Pma1 by endoplasmic reticulum-associated degradation requires Atg19 and the Cvt/autophagy pathway.
Misfolded proteins are usually arrested in the endoplasmic reticulum (ER) and degraded by the ER-associated degradation (ERAD) machinery. Several mutant alleles of PMA1, the gene coding for the plasma membrane H(+)-ATPase, render misfolded proteins that are retained in the ER and degraded by ERAD. A subset of misfolded PMA1 mutants exhibit a dominant negative effect on yeast growth since, when coexpressed with the wild-type allele, both proteins are retained in the ER. We have used a pma1-D378T dominant negative mutant to identify new genes involved in ERAD. A genetic screen was performed for isolation of multicopy suppressors of a GAL1-pma1-D378T allele. ATG19, a member of the cytoplasm to vacuole targeting (Cvt) pathway, was found to suppress the growth arrest phenotype caused by the expression of pma1-D378T. ATG19 accelerates the degradation of pma1-D378T thus allowing the co-retained wild-type Pma1 to reach the plasma membrane. ATG19 was also able to suppress other dominant lethal PMA1 mutations. The degradation of the mutant ATPase occurs in the proteasome and requires intact both ERAD and Cvt/autophagy pathways. We propose the cooperation of both pathways for an efficient degradation of misfolded Pma1.
Mazón
María J
MJ
Departamento de Bioquímica and Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Arturo Duperier, 4, 28029 Madrid, Spain.
Eraso
Pilar
P
Portillo
Francisco
F
D001343:Autophagy / Q000502:physiology*; D003593:Cytoplasm / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D016153:Genes, Suppressor; D009154:Mutation; D017510:Protein Folding; D006180:Proton-Translocating ATPases / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism
D029701:Saccharomyces cerevisiae Proteins; C092477:PMA1 protein, S cerevisiae; D006180:Proton-Translocating ATPases