Peroxisomal catalase deficiency modulates yeast lifespan depending on growth conditions

Exogenous glucosylglycerol and proline extend the chronological lifespan of Rhodosporidium toruloides

Glucosylglycerol (GG) is an osmolyte found in a few bacteria (e.g., cyanobacteria) and plants grown in harsh environments. GG protects microbes and plants from salinity and desiccation stress. In the industry, GG is synthesized from a combination of ADP-glucose and glycerol-3-phosphate in a condensation reaction catalyzed by glucosylglycerol phosphate synthase. Proline, on the other hand, is an amino acid-based osmolyte that plays a key role in cellular reprograming. It functions as a protectant and a scavenger of reactive oxygen species. Studies on lifespan extension have focused on the use of Saccharomyces cerevisiae. Rhodosporidium toruloides, also known as Rhodotorula toruloides, is a basidiomycetous oleaginous yeast known to accumulate lipids to more than 70% of its dry cell weight. The oleaginous red yeast (R. toruloides) has not been intensely studied in the lifespan domain. We designed this work to investigate how GG and proline promote the longevity of this red yeast strain. The results obtained in our study confirmed that these molecules increased R. toruloides' viability, survival percentage, and lifespan upon supplementation. GG exerts the most promising effects at a relatively high concentration (100 mM), while proline functions best at a low level (2 mM). Elucidation of the processes underlying these favorable responses revealed that GG promotes the yeast chronological lifespan (CLS) through increased catalase activity, modulation of the culture medium pH, a rise in ATP, and an increase in reactive oxygen species (ROS) accumulation (mitohormesis). It is critical to understand the mechanisms of these geroprotector molecules, particularly GG, and the proclivity of its lifespan application; this will aid in offering clarity on its potential application in aging research.

Histoplasma capsulatum requires peroxisomes for multiple virulence functions including siderophore biosynthesis

Peroxisomes are versatile eukaryotic organelles essential for many functions in fungi, including fatty acid metabolism, reactive oxygen species detoxification, and secondary metabolite biosynthesis. A suite of Pex proteins (peroxins) maintains peroxisomes, while peroxisomal matrix enzymes execute peroxisome functions. Insertional mutagenesis identified peroxin genes as essential components supporting the intraphagosomal growth of the fungal pathogen Histoplasma capsulatum. Disruption of the peroxins Pex5, Pex10, or Pex33 in H. capsulatum prevented peroxisome import of proteins targeted to the organelle via the PTS1 pathway. This loss of peroxisome protein import limited H. capsulatum intracellular growth in macrophages and attenuated virulence in an acute histoplasmosis infection model. Interruption of the alternate PTS2 import pathway also attenuated H. capsulatum virulence, although only at later time points of infection. The Sid1 and Sid3 siderophore biosynthesis proteins contain a PTS1 peroxisome import signal and localize to the H. capsulatum peroxisome. Loss of either the PTS1 or PTS2 peroxisome import pathway impaired siderophore production and iron acquisition in H. capsulatum, demonstrating compartmentalization of at least some biosynthetic steps for hydroxamate siderophore biosynthesis. However, the loss of PTS1-based peroxisome import caused earlier virulence attenuation than either the loss of PTS2-based protein import or the loss of siderophore biosynthesis, indicating additional PTS1-dependent peroxisomal functions are important for H. capsulatum virulence. Furthermore, disruption of the Pex11 peroxin also attenuated H. capsulatum virulence independently of peroxisomal protein import and siderophore biosynthesis. These findings demonstrate peroxisomes contribute to H. capsulatum pathogenesis by facilitating siderophore biosynthesis and another unidentified role(s) for the organelle during fungal virulence. IMPORTANCE The fungal pathogen Histoplasma capsulatum infects host phagocytes and establishes a replication-permissive niche within the cells. To do so, H. capsulatum overcomes and subverts antifungal defense mechanisms which include the limitation of essential micronutrients. H. capsulatum replication within host cells requires multiple distinct functions of the fungal peroxisome organelle. These peroxisomal functions contribute to H. capsulatum pathogenesis at different times during infection and include peroxisome-dependent biosynthesis of iron-scavenging siderophores to enable fungal proliferation, particularly after activation of cell-mediated immunity. The multiple essential roles of fungal peroxisomes reveal this organelle as a potential but untapped target for the development of therapeutics.

Catalase: A critical node in the regulation of cell fate

Catalase (CAT) is an extensively studied if somewhat enigmatic enzyme that is at the heart of eukaryotic antioxidant systems with a canonical role in peroxisomal function. The CAT family of proteins exert control over a wide range of plant growth and defence processes. CAT proteins are subject to many types of post-translational modification (PTM), which modify activity, ligand binding, stability, compartmentation and function. The CAT interactome involves many cytosolic and nuclear proteins that appear to be essential for protein functions. Hence, the CAT network of roles extends far beyond those associated with peroxisomal metabolism. Some pathogen effector proteins are able to redirect CAT to the nucleus and recent evidence indicates CAT can traffic to the nucleus in the absence of exogenous proteins. While the mechanisms that target CAT to the nucleus are not understood, CAT activity in the cytosol and nucleus is promoted by interactions with nucleoredoxin. Here we discuss recent findings that have been pivotal in generating a step change in our understanding of CAT functions in plant cells.

Dephosphorylation of CatC at Ser-18 improves salt and oxidative tolerance via promoting its tetramerization in rice

Catalase (CAT) is a vital antioxidant enzyme, while phosphorylation pivotally regulates its function. Many phosphosites have been identified in CAT, but their functions remained largely elusive. We functionally studied five phosphoserines (Ser-9, -10, -11, -18, and -205) of CatC in rice (Oryza sativa L.). Phospho-Ser-9 and - 11 and dephospho-Ser-18 promoted the enzymatic activity of CatC and enhanced oxidative and salt tolerance in yeast. Phosphorylation status of Ser-18 did not affect CatC peroxisomal targeting and stability, but dephospho-Ser-18 promoted CatC tetramerization to enhance its activity. Moreover, overexpression of dephospho-mimic form CatC^S18A in rice significantly improved the tolerance to salt and oxidative stresses by inhibiting the H₂O₂ accumulation. Together, these results elucidate the mechanism underlying dephosphorylation at Ser-18 promotes CatC activity and salt tolerance in rice. Ser-18 is a promising candidate phosphosite of CatC for breeding highly salt-tolerant rice.

Glucosylglycerol Extends Chronological Lifespan of the Budding Yeast via an Increased Osmolarity Response

Glucosylglycerol (GG) is an osmolyte that protects cells from extreme conditions. It is produced by sucrose phosphorylase, an enzyme that uses sucrose and glycerol as substrate. GG protects tissue integrity in desert plants during harsh conditions and guards cyanobacteria against high salinity (halotolerant). However, no extensive research has been conducted on the lifespan application of this compound on the yeast Saccharomyces cerevisiae. We designed this study to (1) characterize GG's effect on yeast chronological lifespan (CLS) and (2) to determine the mechanisms underlying its lifespan promotion on strain DBY746. The results obtained in our study confirm that GG causes increased longevity when administered at moderate doses (48 mM and 120 mM). In addition, we discovered that GG promotes yeast cell longevity by increasing the osmolarity of the culture medium. The maximum lifespan increased by approximately 15.38% and 34.6%, (i.e., 115.38 and 134.61) respectively, upon administration of GG at 48 mM and 120 mM concentrations. Elucidation of the mechanisms underlying this positive response suggests that GG promotes CLS by activities that modulate reactive oxygen species (ROS) generation, as evident in its increased ROS generation (mitohormesis). An increase in medium osmolarity caused by GG supplementation triggers ROS production and promotes longevity in the yeast (S. cerevisiae). An in-depth study on the potential application of this molecule in aging research is crucial; this will aid in expounding the mechanisms of this geroprotector and its longevity supportive tendencies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01055-y.

Post-translational modifications of proteins associated with yeast peroxisome membrane: An essential mode of regulatory mechanism

Peroxisomes are single membrane‐bound organelles important for the optimum functioning of eukaryotic cells. Seminal discoveries in the field of peroxisomes are made using yeast as a model. Several proteins required for the biogenesis and function of peroxisomes are identified to date. As with proteins involved in other major cellular pathways, peroxisomal proteins are also subjected to regulatory post‐translational modifications. Identification, characterization and mapping of these modifications to specific amino acid residues on proteins are critical toward understanding their functional significance. Several studies have tried to identify post‐translational modifications of peroxisomal proteins and determine their impact on peroxisome structure and function. In this manuscript, we provide an overview of the various post‐translational modifications that govern the peroxisome dynamics in yeast.

Cell organelles and yeast longevity: an intertwined regulation

Organelles are dynamic structures of a eukaryotic cell that compartmentalize various essential functions and regulate optimum functioning. On the other hand, ageing is an inevitable phenomenon that leads to irreversible cellular damage and affects optimum functioning of cells. Recent research shows compelling evidence that connects organelle dysfunction to ageing-related diseases/disorders. Studies in several model systems including yeast have led to seminal contributions to the field of ageing in uncovering novel pathways, proteins and their functions, identification of pro- and anti-ageing factors and so on. In this review, we present a comprehensive overview of findings that highlight the role of organelles in ageing and ageing-associated functions/pathways in yeast.

Peroxisomes: role in cellular ageing and age related disorders

Peroxisomes are dynamic organelles essential for optimum functioning of a eukaryotic cell. Biogenesis of these organelles and the diverse functions performed by them have been extensively studied in the past decade. Their ability to perform functions depending on the cell type and growth conditions is unique and remarkable. Oxidation of fatty acids and reactive oxygen species metabolism are the two most important functions of these ubiquitous organelles. They are often referred to as both source and sink of reactive oxygen species in a cell. Recent research connects peroxisome dysfunction to fatal oxidative damage associated with ageing-related diseases/disorders. It is now widely accepted that mitochondria and peroxisomes are required to maintain oxidative balance in a cell. However, our understanding on the inter-dependence of these organelles to maintain cellular homeostasis of reactive oxygen species is still in its infancy. Herein, we summarize findings that highlight the role of peroxisomes in cellular reactive oxygen species metabolism, ageing and age-related disorders.

Role/s of 'Antioxidant' Enzymes in Ageing

Reactive oxygen species (ROS), generated externally and during aerobic metabolism, are a potent cause of cell damage. Oxidative damage is a feature of many diseases and ageing, including age-associated diseases, such as diabetes, cancer, cardiovascular and neurodegenerative diseases. Indeed, this association helped lead to the widely expounded 'Free Radical Theory of Aging', proposing that the accumulation of ROS-induced damage is the underlying cause of ageing. In the last decade, it has become apparent that ROS play more complex roles in ageing than simply causing damage. This includes the induction of signalling pathways that protect against/repair cell damage. Cells encode a variety of enzymes that metabolise ROS, some of which reduce them to less reactive species. In this chapter, we review the evidence that manipulating the levels of these enzymes has any effect/s on ageing. We will also highlight a few examples illustrating why it is an over-simplification to describe the activities of some of these enzymes as 'antioxidants'. We discuss how these studies have helped refine our view of how ROS and ROS-metabolising enzymes contribute to the ageing process.

Slm35 links mitochondrial stress response and longevity through TOR signaling pathway

In most eukaryotic cells mitochondria are essential organelles involved in a great variety of cellular functions. One of the physiological processes linked to mitochondria is aging, a gradual process of damage accumulation that eventually promotes cell death. Aging depends on a balance between mitochondrial biogenesis, function and degradation. It has been previously shown that Tor1, Sch9 and Ras2 are activated in response to nutrient availability and regulate cell growth and division. A deficiency in any of these genes promotes lifespan extension and cell protection during oxidative and heat shock stress. In this work we report that in Saccharomyces cerevisiae, the uncharacterized mitochondrial protein Slm35 is functionally linked with the TOR signaling pathway. A Δtor1Δslm35 strain shows a severe decrease in lifespan and is unable to contend with oxidative and heat shock stresses. Specifically, this mutant shows decreased catalase activity indicating a misregulation of ROS scavenging mechanisms. In this study we show that Slm35 is also relevant for mitochondrial network dynamics and mitophagy. The results presented here suggest that Slm35 plays an important role connecting mitochondrial function with cytosolic responses and cell adaptation to stress and aging.

Tethering telomerase to telomeres increases genome instability and promotes chronological aging in yeast

Chronological aging of the yeast Saccharomyces cerevisiae is attributed to multi-faceted traits especially those involving genome instability, and has been considered to be an aging model for post-mitotic cells in higher organisms. Telomeres are the physical ends of eukaryotic chromosomes, and are essential for genome integrity and stability. It remains elusive whether dysregulated telomerase activity affects chronological aging. We employed the CDC13-EST2 fusion gene, which tethers telomerase to telomeres, to examine the effect of constitutively active telomerase on chronological lifespan (CLS). The expression of Cdc13-Est2 fusion protein resulted in overlong telomeres (2 to 4 folds longer than normal telomeres), and long telomeres were stably maintained during long-term chronological aging. Accordingly, genome instability, manifested by accumulation of extra-chromosomal rDNA circle species, age-dependent CAN1 marker-gene mutation frequency and gross chromosomal rearrangement frequency, was significantly elevated. Importantly, inactivation of Sch9, a downstream kinase of the target of rapamycin complex 1 (TORC1), suppressed both the genome instability and accelerated chronological aging mediated by CDC13-EST2 expression. Interestingly, loss of the CDC13-EST2 fusion gene in the cells with overlong telomeres restored the regular CLS. Altogether, these data suggest that constitutively active telomerase is detrimental to the maintenance of genome stability, and promotes chronological aging in yeast.

MET18 Deficiency Increases the Sensitivity of Yeast to Oxidative Stress and Shortens Replicative Lifespan by Inhibiting Catalase Activity

Yeast MET18, a subunit of the cytosolic iron-sulfur (Fe/S) protein assembly (CIA) machinery which is responsible for the maturation of Fe/S proteins, has been reported to participate in the oxidative stress response. However, the underlying molecular mechanisms remain unclear. In this study, we constructed a MET18/met18Δ heterozygous mutant yeast strain and found that MET18 deficiency in yeast cells impaired oxidative stress resistance as evidenced by increased sensitivity to hydrogen peroxide (H₂O₂) and cumene hydroperoxide (CHP). Mechanistically, the mRNA levels of catalase A (CTA1) and catalase T (CTT1) as well as the total catalase activity were significantly reduced in MET18-deficient cells. In contrast, overexpression of CTT1 or CTA1 in MET18-deficient cells significantly increased the intracellular catalase activity and enhanced the resistance ability against H₂O₂ and CHP. In addition, MET18 deficiency diminished the replicative capacity of yeast cells as evidenced by the shortened replicative lifespan, which can be restored by CTT1 overexpression, but not by CTA1, in the MET18-deficient cells. These results suggest that MET18, in a catalase-dependent manner, plays an essential role in enhancing the resistance of yeast cells to oxidative stress and increasing the replicative capacity of yeast cells.

Pro- and Antioxidant Functions of the Peroxisome-Mitochondria Connection and Its Impact on Aging and Disease

Peroxisomes and mitochondria are the main intracellular sources for reactive oxygen species. At the same time, both organelles are critical for the maintenance of a healthy redox balance in the cell. Consequently, failure in the function of both organelles is causally linked to oxidative stress and accelerated aging. However, it has become clear that peroxisomes and mitochondria are much more intimately connected both physiologically and structurally. Both organelles share common fission components to dynamically respond to environmental cues, and the autophagic turnover of both peroxisomes and mitochondria is decisive for cellular homeostasis. Moreover, peroxisomes can physically associate with mitochondria via specific protein complexes. Therefore, the structural and functional connection of both organelles is a critical and dynamic feature in the regulation of oxidative metabolism, whose dynamic nature will be revealed in the future. In this review, we will focus on fundamental aspects of the peroxisome-mitochondria interplay derived from simple models such as yeast and move onto discussing the impact of an impaired peroxisomal and mitochondrial homeostasis on ROS production, aging, and disease in humans.

Starvation signals in yeast are integrated to coordinate metabolic reprogramming and stress response to ensure longevity

Studies on replicative and chronological aging in Saccharomyces cerevisiae have greatly advanced our understanding of how longevity is regulated in all eukaryotes. Chronological lifespan (CLS) of yeast is defined as the age-dependent viability of non-dividing cell populations. A number of nutrient sensing and signal transduction pathways (mainly TOR and PKA) have been shown to regulate CLS, yet it is poorly understood how the starvation signals transduced via these pathways lead to CLS extension. Using reporters whose expressions are induced by glucose starvation, we have screened the majority of the 'signaling' mutants in the yeast genome and identified many genes that are necessary for stress response. Subsequent analyses of the 'signaling' mutants not only revealed novel regulators of CLS, such as the GSK-3 ortholog Mck1, but also demonstrated that starvation signals transmitted by SNF1/AMPK, PKC1 and those negatively regulated by TOR/PKA, including Rim15, Yak1 and Mck1 kinases, are integrated to enable metabolic reprogramming and the acquisition of stress resistance. Coordinated metabolic reprogramming ensures the accumulation of storage carbohydrates for quiescent cells to maintain viability. We provide new evidence that Yak1, Rim15 and Mck1 kinases cooperate to activate H₂O₂-scanvenging activities, thus limiting the levels of ROS in cells entering quiescence. These findings support the recent advances in higher organisms that the flexibility of metabolic reprogramming and the balance between energetics and stress resistance are the unifying principles of lifespan extension. Future work to reveal how the metabolic switch and stress response is coordinated will help delineate the molecular mechanisms of aging in yeast and shed novel insight into aging/anti-aging principles in higher organisms.

Antioxidant cytoprotection by peroxisomal peroxiredoxin-5

Peroxiredoxin-5 (PRDX5) is a thioredoxin peroxidase that reduces hydrogen peroxide, alkyl hydroperoxides, and peroxynitrite. This enzyme is present in the cytosol, mitochondria, peroxisomes, and nucleus in human cells. Antioxidant cytoprotective functions have been previously documented for cytosolic, mitochondrial, and nuclear mammalian PRDX5. However, the exact function of PRDX5 in peroxisomes is still not clear. The aim of this work was to determine the function of peroxisomal PRDX5 in mammalian cells and, more specifically, in glial cells. To study the role of PRDX5 in peroxisomes, the endogenous expression of PRDX5 in murine oligodendrocyte 158N cells was silenced by RNA interference. In addition, human PRDX5 was also overexpressed in peroxisomes using a vector coding for human PRDX5, whose unconventional peroxisomal targeting sequence 1 (PTS1; SQL) was replaced by the prototypical PTS1 SKL. Stable 158N clones were obtained. The antioxidant cytoprotective function of peroxisomal PRDX5 against peroxisomal and mitochondrial KillerRed-mediated reactive oxygen species production as well as H2O2 was examined using MTT viability assays, roGFP2, and C11-BOBIPY probes. Altogether our results show that peroxisomal PRDX5 protects 158N oligodendrocytes against peroxisomal and mitochondrial KillerRed- and H2O2-induced oxidative stress.

Peroxisomal quality control mechanisms

Peroxisomes are ubiquitous organelles that harbor diverse metabolic pathways, which are essential for normal cell performance. Conserved functions of these organelles are hydrogen peroxide metabolism and β-oxidation. Cells employ multiple quality control mechanisms to ensure proper peroxisome function and to protect peroxisomes from damage. These involve the function of molecular chaperones, a peroxisomal Lon protease and autophagic removal of dysfunctional organelles. In addition, multiple mechanisms exist to combat peroxisomal oxidative stress. Here, we outline recent advances in our understanding of peroxisomal quality control, focussing on yeast and filamentous fungi.

Seasonal and plant-dependent variations in diversity, abundance and stress tolerance of epiphytic yeasts in desert habitats

We studied the epiphytic yeast species of the plants of the Negev Desert and the Dead Sea region, Israel, which are considered one of the most extreme hyper-arid lands in the world. For this purpose, we developed isolation protocols; we performed morphological, cultural and molecular identification tests and compared yeast diversity between the locations and the plants. The composition of the yeast populations present in the study's plants underwent seasonal fluctuations, whereas differences in community compositions were significant within sites. The maximum number of species of yeast occurred in autumn and Cryptococcus spp. were predominant year round. The isolated yeast strains showed an unusual tolerance to extreme growth conditions, such as high temperatures (up to 72% viability at 50°C), lethal hydrogen peroxide and NaCl concentrations. These results suggest that epiphytic yeasts inhabit the plants of the Dead Sea region and the Negev Desert have a community structure that is unique to the plant species and have a high tolerance to the harsh conditions that enables them to adapt to an arid ecosystem.

Effect of paraquat-induced oxidative stress on gene expression and aging of the filamentous ascomycete Podospora anserina

Aging of biological systems is influenced by various factors, conditions and processes. Among others, processes allowing organisms to deal with various types of stress are of key importance. In particular, oxidative stress as the result of the generation of reactive oxygen species (ROS) at the mitochondrial respiratory chain and the accumulation of ROS-induced molecular damage has been strongly linked to aging. Here we view the impact of ROS from a different angle: their role in the control of gene expression. We report a genome-wide transcriptome analysis of the fungal aging model Podospora anserina grown on medium containing paraquat (PQ). This treatment leads to an increased cellular generation and release of H₂O₂, a reduced growth rate, and a decrease in lifespan. The combined challenge by PQ and copper has a synergistic negative effect on growth and lifespan. The data from the transcriptome analysis of the wild type cultivated under PQ-stress and their comparison to those of a longitudinal aging study as well as of a copper-uptake longevity mutant of P. anserina revealed that PQ-stress leads to the up-regulation of transcripts coding for components involved in mitochondrial remodeling. PQ also affects the expression of copper-regulated genes suggesting an increase of cytoplasmic copper levels as it has been demonstrated earlier to occur during aging of P. anserina and during senescence of human fibroblasts. This effect may result from the induction of the mitochondrial permeability transition pore via PQ-induced ROS, leading to programmed cell death as part of an evolutionary conserved mechanism involved in biological aging and lifespan control.

Cell-autonomous mechanisms of chronological aging in the yeast Saccharomyces cerevisiae

A body of evidence supports the view that the signaling pathways governing cellular aging - as well as mechanisms of their modulation by longevity-extending genetic, dietary and pharmacological interventions - are conserved across species. The scope of this review is to critically analyze recent advances in our understanding of cell-autonomous mechanisms of chronological aging in the budding yeast Saccharomyces cerevisiae. Based on our analysis, we propose a concept of a biomolecular network underlying the chronology of cellular aging in yeast. The concept posits that such network progresses through a series of lifespan checkpoints. At each of these checkpoints, the intracellular concentrations of some key intermediates and products of certain metabolic pathways - as well as the rates of coordinated flow of such metabolites within an intricate network of intercompartmental communications - are monitored by some checkpoint-specific ʺmaster regulatorʺ proteins. The concept envisions that a synergistic action of these master regulator proteins at certain early-life and late-life checkpoints modulates the rates and efficiencies of progression of such processes as cell metabolism, growth, proliferation, stress resistance, macromolecular homeostasis, survival and death. The concept predicts that, by modulating these vital cellular processes throughout lifespan (i.e., prior to an arrest of cell growth and division, and following such arrest), the checkpoint-specific master regulator proteins orchestrate the development and maintenance of a pro- or anti-aging cellular pattern and, thus, define longevity of chronologically aging yeast.

At neutral pH the chronological lifespan of Hansenula polymorpha increases upon enhancing the carbon source concentrations

Dietary restriction is generally assumed to increase the lifespan in most eukaryotes, including the simple model organism Saccharomyces cerevisiae. However, recent data questioned whether this phenomenon is indeed true for yeast. We studied the effect of reduction of the carbon source concentration on the chronological lifespan of the yeast Hansenula polymorpha using four different carbon sources. Our data indicate that reduction of the carbon source concentration has a negative (glucose, ethanol, methanol) or positive (glycerol) effect on the chronological lifespan. We show that the actual effect of carbon source concentrations largely depends on extracellular factor(s). We provide evidence that H. polymorpha acidifies the medium and that a low pH of the medium alone is sufficient to significantly decrease the chronological lifespan. However, glucose-grown cells are less sensitive to low pH compared to glycerol-grown cells, explaining why only the reduction of the glycerol-concentration (which leads to less medium acidification) has a positive effect on the chronological lifespan. Instead, the positive effect of enhancing the glucose concentrations is much larger than the negative effect of the medium acidification at these conditions, explaining the increased lifespan with increasing glucose concentrations. Importantly, at neutral pH, the chronological lifespan also decreases with a reduction in glycerol concentrations. We show that for glycerol cultures this effect is related to acidification independent changes in the composition of the spent medium. Altogether, our data indicate that in H. polymorpha at neutral pH the chronological lifespan invariably extends upon increasing the carbon source concentration.

The significance of peroxisome function in chronological aging of Saccharomyces cerevisiae

We studied the chronological lifespan of glucose-grown Saccharomyces cerevisiae in relation to the function of intact peroxisomes. We analyzed four different peroxisome-deficient (pex) phenotypes. These included Δpex3 cells that lack peroxisomal membranes and in which all peroxisomal proteins are mislocalized together with Δpex6 in which all matrix proteins are mislocalized to the cytosol, whereas membrane proteins are still correctly sorted to peroxisomal ghosts. In addition, we analyzed two mutants in which the peroxisomal location of the β-oxidation machinery is in part disturbed. We analyzed Δpex7 cells that contain virtually normal peroxisomes, except that all matrix proteins that contain a peroxisomal targeting signal type 2 (PTS2, also including thiolase), are mislocalized to the cytosol. In Δpex5 cells, peroxisomes only contain matrix proteins with a PTS2 in conjunction with all proteins containing a peroxisomal targeting signal type 1 (PTS1, including all β-oxidation enzymes except thiolase) are mislocalized to the cytosol. We show that intact peroxisomes are an important factor in yeast chronological aging because all pex mutants showed a reduced chronological lifespan. The strongest reduction was observed in Δpex5 cells. Our data indicate that this is related to the complete inactivation of the peroxisomal β-oxidation pathway in these cells due to the mislocalization of thiolase. Our studies suggest that during chronological aging, peroxisomal β-oxidation contributes to energy generation by the oxidation of fatty acids that are released by degradation of storage materials and recycled cellular components during carbon starvation conditions.