Biogenesis and turnover of peroxisomes involved in the concurrent oxidation of methanol and methylamine in Hansenula polymorpha |
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Authors: | M Veenhuis K B Zwart W Harder |
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Institution: | (1) Laboratory for Electron Microscopy and Department of Microbiology, Biological Centre, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands |
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Abstract: | Growth of Hansenula polymorpha in shake flasks and chemostat cultures in the presence of methanol as the sole source of carbon and methylamine as the sole
source of nitrogen was associated with the development of peroxisomes in the cells. The organelles were involved in the concurrent
oxidation of these two compounds, since they contained both alcohol oxidase and amine oxidase, which are key enzymes in methanol
and methylamine metabolism, respectively. In addition catalase was present. Peroxisomes with a completely crystalline substructure
were observed in methanol-limited chemostat-grown cells. Amine oxidase probably formed an integral part of these crystalloids,
whereas catalase was present in a freely diffusable form.
Transfer of cells, grown in a methanol-limited chemostat in the presence of methylamine into glucose/ammonium sulphate media
resulted in the loss of both alcohol oxidase and amine oxidase activity from the cells. This process was associated with degradation
of the crystalline peroxisomes. However, when cells were transferred into glucose/methylamine media, amine oxidase activity
only declined during 2 h after the transfer and thereafter increased again. This subsequent rise in amine oxidase activity
was associated with the development of new peroxisomes in the cells in which degradation of the crystalline peroxisomes, originally
present, continued. These newly formed organelles probably originated from peroxisomes which had not been affected by degradation.
When in the methanollimited chemostat methylamine was replaced by ammonium sulphate, repression of the synthesis of amine
oxidase was observed. However, inactivation of this enzyme or degradation of peroxisomes was not detected. The decrease of
amine oxidase activity in the culture was accounted for by dilution of enzyme as a result of growth and washout. |
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Keywords: | Peroxisome Methanol Methylamine Yeast Hansenula polymorpha Alcohol oxidase Amino oxidase Catalase Catabolite inactivation Turnover Cytochemical localization |
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