Project Details
Projekt
Evolutionary dynamics of peroxisome functions and biogenesis facilitating plant terrestrialization
Applicant
Professorin Dr. Sigrun Reumann
Subject Area
Cell Biology
Term
since 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 528117925
The colonization of the land by plants was a key event in evolution and has transformed the planet. In their subaerial and terrestrial habitats, streptophyte algae and early land plants encountered multiple abiotic stresses and evolved adaptative mechanisms. Despite considerable progress, we are only in the beginning of understanding the cell biology of streptohyte algae. Peroxisomes are important cell organelles not only for fatty acid β-oxidation and photorespiration, but also for ROS detoxification and homeostasis, hormone biosynthesis, and abiotic stress tolerance. We want to identify key innovations of peroxisomes that were required for plant terrestrialization. We first addressed (i) to what extent peroxisome functions known from land plants are conserved in streptophyte algae and (ii) in which order they evolved. Using the protein landscape of Arabidopsis peroxisomes, we analyzed the conservation of matrix proteins and peroxisome localization at genome scale in streptophytes in comparison to chlorophytes. Accordingly, several peroxisome functions of land plants are conserved in chlorophytes. More advanced peroxisome functions, however, apparently evolved either after the divergence of Mesostigmatophyceae (e.g., fully established photorespiration), after that of Klebsormidiophyceae (e.g., NADPH production), or after the branching of Charophyceae (e.g., benzaldehyde biosynthesis). Furthermore, our data newly indicate that the peculiar, peroxisome-specific mechanism of “piggy-back import” may have been crucial to allow the simultaneous re-direction of neighboring pathway enzymes into peroxisomes. In this proposed research project, we want to extend our bioinformatic analyses and include further genomes of streptophyte algae and also transcriptome data (WP1). To identify new functions of streptophyte peroxisomes, we want to predict the entire matrix proteome of peroxisomes for 10 selected genomes of streptophytes in comparison to chlorophytes. Peroxisome targeting of proteins from selected streptophytes shall be verified experimentally (WP2). We will focus on (i) predicted peroxisomal proteins with non-canonical PTS and (ii) proteins of specific metabolic pathways and from extant species that are located close to the predicted point of divergence in subcellular compartmentalization. The genes will be cloned from streptophytic model algae and expressed as fluorescent fusions, first in the well-established system of Arabidopsis and for selected proteins also in the new model alga of Zygnematophyceae, Spirogyra pratensis. To allow comprehensive analyses of subcellular targeting in Spirogyra, we will create a set of transient expression vectors for the MadLand2 community. In WP3 we will investigate whether specific peroxisomal matrix enzymes of streptophytes can indeed import a neighboring pathway enzyme that lacks any PTS into peroxisomes by experimental analyses of protein-protein interactions and protein import by piggy-back mechanism.
DFG Programme
Priority Programmes
