Peroxisome Maintenance Depends on De Novo Peroxisome Formation in Yeast Mutants Defective in Peroxisome Fission and Inheritance.

Justyna P Wróblewska,Ida J Van Der Klei

doi:10.3390/ijms20164023

Justyna P Wróblewska, Ida J Van Der Klei

Open Access

https://doi.org/10.3390/ijms20164023

Copy DOI

Abstract

There is an ongoing debate on how peroxisomes form: by growth and fission of pre-existing peroxisomes or de novo from another membrane. It has been proposed that, in wild type yeast cells, peroxisome fission and careful segregation of the organelles over mother cells and buds is essential for organelle maintenance. Using live cell imaging we observed that cells of the yeast Hansenula polymorpha, lacking the peroxisome fission protein Pex11, still show peroxisome fission and inheritance. Also, in cells of mutants without the peroxisome inheritance protein Inp2 peroxisome segregation can still occur. In contrast, peroxisome fission and inheritance were not observed in cells of a pex11 inp2 double deletion strain. In buds of cells of this double mutant, new organelles likely appear de novo. Growth of pex11 inp2 cells on methanol, a growth substrate that requires functional peroxisomes, is retarded relative to the wild type control. Based on these observations we conclude that in H. polymorpha de novo peroxisome formation is a rescue mechanism, which is less efficient than organelle fission and inheritance to maintain functional peroxisomes.

Highlights

Peroxisomes are important organelles widely distributed among eukaryotic organisms
In cells lacking the peroxisome inheritance factor Inp2, peroxisomal structures can still move to the nascent buds
When both Pex11 and Inp2 are absent, a substantial percentage of cells lacking peroxisomes are formed, suggesting that both fission and inheritance are blocked. These peroxisome-deficient cells become capable of growing on methanol medium, indicating that new peroxisomes form in these cells

Summary

Introduction

Peroxisomes are important organelles widely distributed among eukaryotic organisms. These organelles compartmentalize a variety of specific metabolic processes [1,2,3]. Peroxisomes are important for the metabolism of various unusual carbon and nitrogen sources, such as oleic acid, methanol, primary amines and uric acid [4]. Peroxisome proliferation is repressed during growth of cells on media that do not require peroxisomal enzymes (e.g., glucose). Upon shifting H. polymorpha cells from glucose- to methanol-containing medium peroxisome proliferation is strongly induced [7]. This property renders H. polymorpha an attractive model organism to study peroxisome formation

Methods

Results

Conclusion