Research interest

The lab is interested in the molecular basis and cellular role of cytoskeleton-based dynamics. Making use of the fungal model system Ustilago maydis we address fundamental cell biological questions, such as the organization and function of the microtubule cytoskeleton (Figure 1). This fungal model system combines technical advantages (molecular genetics, published genome, excellent live cell imaging) with biological similarities to animal cells on both genomic and functional levels. This enables us to address important cellular processes relevant for higher eukaryotes that cannot be addressed in other fungal model organisms such as Saccharomyces cerevisiae or Schizosaccaromyces pombe. Recently, we focussed on motor cooperation in secretion (Research Topic B) and early endosome motility (Research Topic C), using a combination of high end quantitative live cell imaging, molecular genetics, biochemistry and mathematical modelling (Figure 2).

The second major emphasis of the group is on the cellular basis of fungal infections. U. maydis is an important plant pathogen that causes smut disease on corn. It switches between a yeast-like and hyphal stage (Figure 1) and is able to infect maize plants (see Model System). With the wheat pathogen Mycosphaerella graminicola (anamorph: Septoria tritici , the cause of wheat leaf blotch) we have established a second model fungus (see Model System). Using both important pathogens, we are aiming to understand the role of the cytoskeleton and associated membrane trafficking in plant infection. Thus, our work aims to answer fundamental cell biology questions, but also provides important insights into the basis of fungal plant pathogenicity.

Research Topic A - Microtubule organisation and interphase function

Microtubules serve as tracks for intracellular motility. This topic focuses on the mechanism by which the interphase microtubule array gets organized. Furthermore, some work addresses the role of the cytoskeleton, and in particular of the prominent microtubule array. More information

Research Topic B - Molecular motors in hyphal growth and pathogenicity of U. maydis

We have identified and cloned all motors in U. maydis. This research topic addresses their function, role and their cooperation in fungal growth and pathogenicity. More information

Research Topic C - Endocytosis and early endosome motility

We discovered that hyphal growth and pathogenicity of U. maydis requires endocytosis, which involves rapidly moving early endosomes. Their biological function, as well as the molecular basis of early endosome motility is the focus of this research area. More information

Research Topic D - Dynamics of nuclear pores and open mitosis

The removal of the nuclear envelope in mitosis is characteristic for mammalian cells, whereas fungi are thought to form the mitotic spindle within the closed nuclear envelope. However, U. maydis removes the envelope in mitosis. This coincides with the disassembly of nuclear pores. In addition, we found that nuclear pores are highly dynamic during interphase. This research topic addresses the mechanism and dynamics of the nuclear pores in U. maydis. More information

Research Topic E - U. maydis, a model for cell biology

This is a new project that aims to make use of U. maydis to address the function of conserved hypothetical proteins that are not present in other fungal model systems. More information

Dimorphism of Ustilago maydis

Figure 1: Dimorphism of Ustilago maydis. Yeast-like cells and hyphae contain a prominent microtubule array (green). Laboratory strains contain single nuclei, whereas infective hyphae in nature are dikaryotic (image modified from Steinberg and Perez-Martin, 2008, Trends Cell Biol. 18:61).

Figure 2: Upper panel: A two-lane model describes the behaviour of dynein at the end of microtubules in U. maydis. The model is based on Ashwin et al. 2010, Phys. Rev. E, 82:051907 .Lower panels: Comparison of kymographs of dynein motility derived from the two-lane model showing computer simulations (Simulation) and experimental observation (Experiment). Figure B was taken from Schuster et al., 2011, EMBO J. 30: 652. The bars represent micrometers and seconds.