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Occurrence of peroxisomal membrane proteins in methylotrophic yeasts grown under different conditions
G J Sulter1, L Looyenga, M Veenhuis
1Department of Microbiology, University of Groningen, Haren, The Netherlands.
Abstract:
We have studied the substructure and polypeptide composition of the peroxisomal membranes in two methylotrophic yeasts in relation to different growth conditions. The results obtained indicated that no significant ultrastructural differences existed between the membranes of variously grown cells. The presence of specific peroxisomal membrane proteins (PMPs) was studied biochemically. On sodium dodecyl sulphate-polyacrylamide gels of purified microbody membranes isolated from methanol-grown Hansenula polymorpha, prominent protein bands were observed at 22, 31, 35, 42, 49 and 51 kD. These proteins were also present when the cells were grown in media containing ethanol and/or ethylamine. Apart from these, several other PMPs were specifically induced under these conditions, namely 24, 29, 37 and 62 kD proteins. The polypeptide composition of peroxisomal membranes from H. polymorpha was compared with that of another methylotroph, Candida biodinii. In the latter organism a specific PMP with a molecular weight of 23 kD was induced during growth on D-alanine instead of ammonium sulphate as the nitrogen source.
Insights
This study investigated peroxisomal membrane proteins (PMPs) in methylotrophic yeasts under various growth conditions. Results show distinct PMP profiles, with specific proteins induced by different carbon and nitrogen sources, highlighting adaptive membrane composition.
Area of Science:
- Biochemistry
- Cell Biology
- Microbiology
Background:
- Peroxisomal membranes (PMPs) are crucial for yeast metabolism.
- Understanding PMP composition under diverse growth conditions is essential for elucidating yeast adaptation.
Purpose of the Study:
- To analyze the substructure and polypeptide composition of peroxisomal membranes in methylotrophic yeasts.
- To identify specific peroxisomal membrane proteins (PMPs) induced by different growth conditions.
Main Methods:
- Biochemical analysis of purified microbody membranes using SDS-PAGE.
- Comparative study of Hansenula polymorpha and Candida biodinii under varied growth media.
Main Results:
- No significant ultrastructural differences were observed in peroxisomal membranes across different growth conditions.
- Hansenula polymorpha exhibited distinct PMP profiles, with specific proteins (22, 31, 35, 42, 49, 51 kD) consistently present and others (24, 29, 37, 62 kD) induced by methanol, ethanol, or ethylamine.
- Candida biodinii showed a specific 23 kD PMP induction when grown on D-alanine compared to ammonium sulphate.
Conclusions:
- Peroxisomal membrane protein composition is adaptable and responsive to specific nutrient availability in methylotrophic yeasts.
- The findings contribute to understanding the molecular mechanisms of peroxisome biogenesis and function in response to environmental cues.