Peroxisomal remnants in peroxisome-deficient mutants of the yeast Hansenula polymorpha

We have analyzed the presence of peroxisomal remnants ('ghosts') in three peroxisome-deficient (per) mutants of the yeast Hansenula polymorpha, namely Delta per4, Delta per5 and Delta per10. Under peroxisome-inducing growth conditions peroxisomal membrane proteins (PMPs) mere normally synthesized in cells of these mutants. In addition, these cells contained clusters of small membranous vesicles, which were absent in cells grown under peroxisome-repressing growth conditions. These structures displayed typical peroxisomal properties in that they proliferated upon overproduction of Per8p, the H. polymorpha peroxisome proliferation factor. Moreover, in Delta per4 and Delta per5 these vesicles were susceptible to glucose-induced proteolytic degradation