Characterization of peroxisome-deficient mutants of Hansenula polymorpha

Research paper by Xuqiu Tan, Vladimir I. Titorenko, Ida J. van der Klei, Grietje J. Sulter, Peter Haima, Hans R. Waterham, Melchior Evers, Wim Harder, Marten Veenhuis, James M. Cregg

Indexed on: 01 Aug '95Published on: 01 Aug '95Published in: Current Genetics


In the methylotrophic yeast Hansenula polymorpha, approximately 25% of all methanol-utilization-defective (Mut-) mutants are affected in genes required for peroxisome biogenesis (PER genes). Previously, we reported that one group of per mutants, termed Pim-, are characterized by the presence of a few small peroxisomes with the bulk of peroxisomal enzymes located in the cytosol. Here, we describe a second major group of per mutants that were observed to be devoid of any peroxisome-like structure (Per-). In each Per- mutant, the peroxisomal methanol-pathway enzymes alcohol oxidase, catalase and dihydroxyacetone synthase were present and active but located in the cytosol. Together, the Pim- and Per- mutant collections involved mutations in 14 different PER genes. Two of the genes, PER5 and PER7, were represented by both dominant-negative and recessive alleles. Diploids resulting from crosses of dominant per strains and wild-type H. polymorpha were Mut- and harbored peroxisomes with abnormal morphology. This is the first report of dominant-negative mutations affecting peroxisome biogenesis.