Fate and role of peroxisomes during the life cycle of the yeast Saccharomyces cerevisiae : inheritance of peroxisomes during meiosis

Abstract

Sporulation in the yeast Saccharormyces cerevisiae is a meiotic developmental process that occurs in MATa/MATalpha heterozygotes in response to nutrient deprivation. Here, the fate and role of peroxisomes during sporulation and germination has been examined by a combination of immunoelectron microscopy and the use of pex mutants defective in peroxisomal functions. Using a green fluorescent protein probe targeted to peroxisomes we show that peroxisomes are inherited through meiosis and that they do not increase in number either during sporulation or spore germination. In addition, there is no requirement for peroxisome degradation prior to spore packaging. Unlike the situation in filamentous fungi, peroxisomes do not proliferate during the yeast life cycle. Functional peroxisomes are dispensable for efficient meiotic development on acetate medium since homozygous delta pex6 diploids sporulated well and produced mature spores that were resistant to diethyl ether. Like haploids, diploid cells can proliferate their peroxisomes in response to oleate as sole carbon source in liquid medium, but under these conditions they do not sporulate. On solid oleate medium, homozygous pex5, delta pex6, and pex7 cells were unable to sporulate efficiently, whereas the wild type was. The results presented here are discussed in terms of the transmission of organelles to progeny cells.

Targeting of malate synthase 1 to the peroxisomes of Saccharomyces cerevisiae cells depends on growth on oleic acid medium

“…The requirement for the compartmentalization of the yeast glyoxylate cycle into peroxisomes has been put into question in light of chronicled observations of growth of S. cerevisiae pex mutants devoid of functional peroxisomes on ethanol [19]. In addition, pex mutants have also been demonstrated to undergo normal meiosis and sporulation in liquid acetate medium [33], processes which similarly require a functional glyoxylate cycle [34]. However, as pex mutants fail to grow or sporulate in liquid oleic acid medium [33], the issue of the partitioning of the glyoxylate cycle in cells grown under fatty acid‐medium conditions has hitherto remained open.…”

“…In addition, pex mutants have also been demonstrated to undergo normal meiosis and sporulation in liquid acetate medium [33], processes which similarly require a functional glyoxylate cycle [34]. However, as pex mutants fail to grow or sporulate in liquid oleic acid medium [33], the issue of the partitioning of the glyoxylate cycle in cells grown under fatty acid‐medium conditions has hitherto remained open.…”

Peroxisomes and sexual development in fungi

“…Thus, peroxisomes are partitioned during sporulation. During this process, the number and distribution of peroxisomes are not significantly altered in S. cerevisiae (Gurvitz et al, 1998). Interestingly, the number, size and localization of peroxisomes is tightly regulated during the sexual development in filamentous Ascomycetes.…”

The Difference in Recognition of Terminal Tripeptides as Peroxisomal Targeting Signal 1 between Yeast and Human Is Due to Different Affinities of Their Receptor Pex5p to the Cognate Signal and to Residues Adjacent to It

“…Localization of GFP-SKL (plasmid pJR233) to yeast peroxisomes, seen here as a punctate pattern using fluorescence microscopy, has been amply demonstrated before by immunoelectron microscopy (32,48) and is shown using CB80 cells expressing GFP extended by the SKL-terminating peptide Sc02 (Fig. 1A).…”