The role of the manganese exporter Mnx in manganese homeostasis of photoautotrophs
Manganese (Mn) plays a crucial role as essential micronutrient in all organisms, since it is an important co-factor for different enzymes, such as glycosyl transferases, ligninase, oxalate oxidase or Mn-dependent superoxide dismutase. In addition, photosynthetic organisms rely on sufficient supply of Mn to form the oxygen evolving complex (OEC), which is essential for photosynthesis by driving the oxidation of H2O as electron source for photosystem II. Nevertheless, Mn has detrimental effects if accumulating in higher concentrations inside of cell, since Mn excess may cause mismetalation of metalloproteins. Therefore, proper homeostasis is crucial to avoid an excess on the one hand, but also ensure sufficient Mn supply of the OEC on the other hand.
So far, only few studies have been published, which deal with Mn transport at the chloroplast envelope or thylakoid membrane system, the most critical sides for regulating Mn homeostasis in photoautotrophs. Our group has identified members of the unknown protein family 0016 (UPF0016) for facilitating Mn transport at the thylakoid membrane and the chloroplast envelope in the cyanobacterium Synechocystissp. PCC 6803 and the model plant Arabidopsis thaliana.
In my PhD project, I am investigating additional members of the UPF0016 protein family. Besides the analysis of their specific role in Mn homeostasis I will also address the evolution of the protein family. Since cyanobacteria are the evolutionary ancestors of plant chloroplasts, they are perfect model organisms to perform those studies. To understand why also non-photosynthetic plastids have a strict requirement for Mn I will test candidate proteins for their Mn dependency.
Starting date: 01.11.2020 / Associated Doctoral Researcher
Thesis committee members: Marion Eisenhut, Shizue Matsubara, Nicole Linka