The Hansenula polymorpha PDD1 gene product, essential for the selective degradation of peroxisomes, is a homologue of Saccharomyces cerevisiae Vps34p

Via functional complementation we have isolated the Hansenula polymorpha PD D1 gene essential for selective, macroautophagic peroxisome degradation. Hp PDD1 encodes a 116 kDa protein with high similarity (42% identity) to Sacch aromyces cerevisiae Vps34p, which has been implicated in vacuolar protein s orting and endocytosis. Western blotting experiments revealed that HpPDD1 i s expressed constitutively. In a H. polymorpha padd1 disruption strain pero xisome degradation is fully impaired. Sequestered peroxisomes, typical for the first stage of peroxisome degradation in H. polymorpha, were never obse rved, suggesting that HpPdd1p plays a role in the tagging of redundant pero xisomes and/or sequestration of these organelles from the cytosol. Possibly , HpPdd1p is the functional homologue of ScVps34p, because-like S. cerevisi ae vps34 mutants-H. polymorpha pdd1 mutants are temperature-sensitive for g rowth and are impaired in the sorting of vacuolar carboxypeptidase Y. Moreo ver, HpPdd1p is associated to membranes, as was also observed for ScVps34p. Copyright (C) 1999 John Wiley & Sons, Ltd.