Peroxisomal Membrane Proteome

Peroxisomes are single membrane-bounded organelles present in virtually all eukaryotic cells. These organelles play an important role in the cellular metabolism, which is illustrated by the occurrence of severe human diseases that are correlated with defects in peroxisome biogenesis and metabolism, like e.g. Zellweger syndrome and adrenoleuko dystrophy. However, the knowledge about the proteins associated with and integrated into the peroxisomal membrane is limited. To fully appreciate the role of peroxisomes for living organisms it is essential to identify the proteins responsible for the interplay of the organelle with its environment. The proteomic approach described in this proposal will permit also the identification of low-abundant proteins, which is an essential improvement compared to previous approaches. It consists of a novel isolation method for highly purified and intact peroxisomes combined with biochemical fractionation and enrichment for membrane proteins followed by mass spectrometric identification. The results from these experiments will contribute to complete the picture about the role and function of peroxisomes in the cell. Using state-of-the-art technology established in the Department this project will lead to the identification of all proteins associated with the peroxisomal membrane of the yeast Saccharomyces cerevisiae. This yeast has provided invaluable service as a model system for studying peroxisomes, and many of the known 32 proteins essential for the biogenesis of peroxisomes were originally identified in this yeast. Its fully sequenced genome, its genetic amenability, the simplicity of inducing its peroxisomes to proliferate, and the overall similarity to the situation in higher eukaryotes are further arguments to employ S. cerevisiae as a eukaryotic model system for the identification and characterization of protein function and metabolic pathways. The knowledge about peroxisomal membrane proteins is a necessary requirement for a deeper understanding of the intracellular organization and the interaction between these organelles and their environment. The role and function of proteins found to be associated with peroxisomes for the first time will be further analyzed.

Peroxisomes are single membrane-bounded organelles present in virtually all eukaryotic cells. These organelles play an important role in the cellular metabolism, which is illustrated by the occurrence of severe human diseases that are correlated with defects in peroxisome biogenesis and metabolism, like e.g. Zellweger syndrome and adrenoleuko-dystrophy. However, the knowledge about the proteins associated with and integrated into the peroxisomal membrane is limited. To fully appreciate the role of peroxisomes for living organisms it is essential to identify the proteins responsible for the interplay of the organelle with its environment. The proteomic approach described in this proposal will permit also the identification of low-abundant proteins, which is an essential improvement compared to previous approaches. It consists of a novel isolation method for highly purified and intact peroxisomes combined with biochemical fractionation and enrichment for membrane proteins followed by mass spectrometric identification. The results from these experiments will contribute to complete the picture about the role and function of peroxisomes in the cell. Using state-of-the-art technology established in the Department this project will lead to the identification of all proteins associated with the peroxisomal membrane of the yeast Saccharomyces cerevisiae. This yeast has provided invaluable service as a model system for studying peroxisomes, and many of the known 32 proteins essential for the biogenesis of peroxisomes were originally identified in this yeast. Its fully sequenced genome, its genetic amenability, the simplicity of inducing its peroxisomes to proliferate, and the overall similarity to the situation in higher eukaryotes are further arguments to employ S. cerevisiae as a eukaryotic model system for the identification and characterization of protein function and metabolic pathways. The knowledge about peroxisomal membrane proteins is a necessary requirement for a deeper understanding of the intracellular organization and the interaction between these organelles and their environment. The role and function of proteins found to be associated with peroxisomes for the first time will be further analyzed.