The role of peroxisomes in algae with complex subcellular compartmentalization

• Applicant: Professor Dr. Uwe Gallus Maier, since 9/2020
• Subject Area: Plant Cell and Developmental Biology ; Plant Physiology
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 409750538

Peroxisomes are metabolically versatile organelles present in the majority of eukaryotic cells. Their most common metabolic functions are detoxification of reactive oxygen species and degradation of fatty acids. Although peroxisomes and their derivatives (glyoxysomes, glycosomes and Woronin bodies) have been intensely investigated in certain model-organisms - predominantly mammals, fungi and higher plants - the presence and functions of these organelles in many other eukaryotes is enigmatic. This is particularly true for single-celled eukaryotes, many of which are photosynthetic (algae). Thanks to rapid advances in the field of genomics, cell and molecular biology, studies on peroxisomes in these life forms are feasible.In order to expand knowledge of peroxisomes and their derivatives in eukaryotes we will focus on the role of these organelles in highly compartmentalized organisms that originated by an endosymbiosis of two different eukaryotic cells. We will investigate peroxisomes in the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans, algae with so-called complex plastids that go back to former red or green algal endosymbionts, respectively. The roles of peroxisomes to the cellular metabolism of these complex organisms are completely unknown, but my preliminary work suggests that metabolically active peroxisomes with in part unusual capacities are present in these life forms.In addition to carrying out extensive bioinformatic screens for peroxisome-localized proteins and reconstruction of metabolic networks in cryptophytes and chlorarachniophytes, we will use homologous and heterologous localization studies via expression of fluorescent-tagged proteins and immuno-electron microscopy to analyze peroxisomes in the organisms of interest. In addition, we will introduce a peroxisomal protein targeting pathway from a cryptophyte into a diatom, which is naturally lacking this system, to study the minimal composition and molecular mechanisms of the pathway. Our results will advance knowledge in the fields of cell biology, endosymbiosis, parasitology and, more generally, the evolution and functions of metabolic compartmentalization in microbial eukaryotes.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Dr. Daniel Moog, until 8/2020