title: Transcriptional down-regulation of peroxisome numbers affects selective peroxisome degradation in Hansenula polymorpha.
abstract: We have isolated and characterized a novel transcription factor of Hansenula polymorpha that is involved in the regulation of peroxisomal protein levels. This protein, designated Mpp1p, belongs to the family of Zn(II)2Cys6 proteins. In cells deleted for the function of Mpp1p the levels of various proteins involved in peroxisome biogenesis (peroxins) and function (enzymes) are reduced compared with wild type or, in the case of the matrix protein dihydroxyacetone synthase, fully absent. Also, upon induction of mpp1 cells on methanol, the number of peroxisomes was strongly reduced relative to wild type cells and generally amounted to one organelle per cell. Remarkably, this single organelle was not susceptible to selective peroxisome degradation (pexophagy) and remained unaffected during exposure of methanol-induced cells to excess glucose conditions. We show that this mechanism is a general phenomenon in H. polymorpha in the case of cells that contain only a single peroxisome.
authors.affiliation: Eukaryotic Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren 9750 AA, The Netherlands.
authors.forename: Adriana Nívea
authors.initials: AN
authors.lastname: Leao-Helder
authors.forename: Arjen M
authors.initials: AM
authors.lastname: Krikken
authors.forename: Ida J
authors.initials: IJ
authors.lastname: van der Klei
authors.forename: Jan A K W
authors.initials: JA
authors.lastname: Kiel
authors.forename: Marten
authors.initials: M
authors.lastname: Veenhuis
mesh_terms: D019880:Aldehyde-Ketone Transferases / Q000378:metabolism; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D015536:Down-Regulation; D005947:Glucose / Q000378:metabolism; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D000432:Methanol / Q000494:pharmacology; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D020675:Peroxisomes / Q000378:metabolism*; D010843:Pichia / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics; D014158:Transcription, Genetic; D015032:Zinc / Q000737:chemistry; D016335:Zinc Fingers
chemical_list: D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D004247:DNA; D019880:Aldehyde-Ketone Transferases; C031222:formaldehyde transketolase; D005947:Glucose; D015032:Zinc; D000432:Methanol