Genetic Dissection of Vps13 Regulation in Yeast Using Disease Mutations from Human Orthologs.

The VPS13 family of proteins have emerged as key players in intracellular lipid transport and human health. Humans have four different orthologs, the dysfunction of which leads to different diseases. Yeast has a single gene, which encodes a protein that localizes to multiple different membrane contact sites. The yeast Δ mutant is pleiotropic, exhibiting defects in sporulation, protein trafficking, endoplasmic reticulum (ER)-phagy and mitochondrial function. Non-null alleles resulting from missense mutations can be useful reagents for understanding the multiple functions of a gene. The exceptionally large size of Vps13 makes the identification of key residues challenging. As a means to identify critical residues in yeast Vps13, amino acid substitution mutations from , , and , associated with human disease, were introduced at the cognate positions of yeast , some of which created separation-of-function alleles. Phenotypic analyses of these mutants have revealed that the promotion of ER-phagy is a fourth, genetically separable role of and provide evidence that co-adaptors at the endosome mediate the activity of in vacuolar sorting.