# The yeast peroxisomal proteome at absolute quantitative scale

## TL;DR

This study quantifies peroxisomal proteins in yeast under different metabolic conditions, revealing significant changes in abundance linked to lipid metabolism.

## Contribution

First absolute quantification of the yeast peroxisomal proteome using label-free mass spectrometry under varying metabolic conditions.

## Key findings

- Peroxisomal proteome is threefold more abundant in oleate-grown cells compared to glucose.
- Core peroxisomal proteins show ninefold higher abundance in oleate, emphasizing roles in fatty acid oxidation.
- Proteins involved in import machinery show only moderate abundance changes between conditions.

## Abstract

Peroxisomes are dynamic organelles vital for lipid metabolism and redox homeostasis. In Saccharomyces cerevisiae, the expression of peroxisomal proteins is tightly regulated in response to metabolic conditions. Here, we provide the first absolute quantification of the yeast peroxisomal proteome under peroxisome-inducing (oleate) and fermentative (glucose) conditions using a label-free mass spectrometry approach. We determined protein copy numbers for ~ 4500 proteins, including 99 peroxisomal and peroxisome-associated proteins. Our data reveal that the overall peroxisomal proteome is approximately threefold more abundant in oleate-grown cells, constituting 2.8% (2.01 × 106 protein copies) of the total proteome compared to 0.8% (6.67 × 105 protein copies) in glucose. Considering only peroxisomal core proteins, i.e., proteins exclusively or predominantly localized in peroxisomes, total copy numbers for peroxisomal proteins were even ninefold higher on oleate (0.9%, 6.29 × 105 protein copies) compared to glucose (0.1%, 7.78 × 104 protein copies), reflecting the necessity for peroxisomal functions such as fatty acid beta-oxidation. Enzymes of the beta-oxidation and glyoxylate cycle showed up to > 500-fold higher abundance in oleate. In contrast, core components of the peroxisomal protein import machinery (e.g., Pex5, Pex14) exhibited only moderate changes (~ 2- to 8-fold). In addition to metabolic enzymes and components of the peroxisomal protein import pathways, we provide copy number data for proteins involved in cellular stress response, peroxisome proliferation, division and organization, peroxisome-associated membrane contact sites, and metabolite transporter. Taken together, our dataset offers a quantitative framework of peroxisomal remodeling under different metabolic conditions and highlights the organelle’s adaptive flexibility, providing a valuable resource for future studies on peroxisome biology.

The online version contains supplementary material available at 10.1007/s00418-026-02458-w.