Peroxisome Maintenance Depends on De Novo Peroxisome Formation in Yeast Mutants Defective in Peroxisome Fission and Inheritance.

There is an ongoing debate on how peroxisomes form: by growth and fission of pre-existing peroxisomes or de novo from another membrane. It has been proposed that, in wild type yeast cells, peroxisome fission and careful segregation of the organelles over mother cells and buds is essential for organelle maintenance. Using live cell imaging we observed that cells of the yeast , lacking the peroxisome fission protein Pex11, still show peroxisome fission and inheritance.

Saccharomyces cerevisiae cells lacking Pex3 contain membrane vesicles that harbor a subset of peroxisomal membrane proteins.

Pex3 has been proposed to be important for the exit of peroxisomal membrane proteins (PMPs) from the ER, based on the observation that PMPs accumulate at the ER in Saccharomyces cerevisiae pex3 mutant cells. Using a combination of microscopy and biochemical approaches, we show that a subset of the PMPs, including the receptor docking protein Pex14, localizes to membrane vesicles in S. cerevisiae pex3 cells.