De Novo Peroxisome Biogenesis in Penicillium Chrysogenum Is Not Dependent on the Pex11 Family Members or Pex16

Łukasz Opaliński,Marten Veenhuis,Haiyin Liu,Ida Van Der Klei,Susan Fekken,Magdalena Bartoszewska,Rinse De Boer,Jan A K W Kiel,Jae-Hyuk Yu

doi:10.1371/journal.pone.0035490

Abstract

We have analyzed the role of the three members of the Pex11 protein family in peroxisome formation in the filamentous fungus Penicillium chrysogenum. Two of these, Pex11 and Pex11C, are components of the peroxisomal membrane, while Pex11B is present at the endoplasmic reticulum. We show that Pex11 is a major factor involved in peroxisome proliferation. We also demonstrate that P. chrysogenum cells deleted for known peroxisome fission factors (all Pex11 family proteins and Vps1) still contain peroxisomes. Interestingly, we find that, unlike in mammals, Pex16 is not essential for peroxisome biogenesis in P. chrysogenum, as partially functional peroxisomes are present in a pex16 deletion strain. We also show that Pex16 is not involved in de novo biogenesis of peroxisomes, as peroxisomes were still present in quadruple Δpex11 Δpex11B Δpex11C Δpex16 mutant cells. By contrast, pex3 deletion in P. chrysogenum led to cells devoid of peroxisomes, suggesting that Pex3 may function independently of Pex16. Finally, we demonstrate that the presence of intact peroxisomes is important for the efficiency of ß-lactam antibiotics production by P. chrysogenum. Remarkably, distinct from earlier results with low penicillin producing laboratory strains, upregulation of peroxisome numbers in a high producing P. chrysogenum strain had no significant effect on penicillin production.

Highlights

Peroxisomes represent a class of important organelles that are characterized by an unprecedented functional plasticity that varies with the organism in which they occur and the environmental conditions
Filamentous ascomycetes like P. chrysogenum lack a Pex25 ortholog, which was shown to be essential in the yeast Hansenula polymorpha for de novo peroxisome formation from the endoplasmic reticulum (ER) [7]
We have analyzed the function of the members of the Pex11 protein family Pex11, Pex11B and Pex11C as well as Pex16 in peroxisome formation and penicillin production in the fungus P. chrysogenum

Summary

Introduction

Peroxisomes represent a class of important organelles that are characterized by an unprecedented functional plasticity that varies with the organism in which they occur and the environmental conditions. Peroxisomes play a crucial role in the metabolism of various unusual components used for growth (Nand C-sources), the detoxification of reactive oxygen species as well as the formation of specific secondary metabolites, e.g. ßlactam antibiotics [1,2,3,4]. In these organisms proliferation of peroxisomes is generally induced when the cells are placed at conditions that require the function of peroxisomal enzymes for growth, such as fatty acids [3]. In this yeast peroxisome biogenesis is fully inhibited when both de novo formation from the ER (by deletion of Hp-PEX25) and fission (by deletion of Hp-PEX11) are simultaneously blocked [7]

Methods

Results

Conclusion