The plant pathogenic fungus Ustilago maydis induces disease only in its dikaryotic stage that is generated after mating. This process involves coordinated cAMP and mitogen-activated protein kinase signalling to regulate transcriptional as well as morphological responses. Among the induced products is the key regulator for pathogenic development. Recent advances identified crucial nodes that int...

Accumulation of 14alpha-methylated sterols or delta8-sterols in Ustilago maydis affected three aspects of the plasma membrane H+-ATPase. Proton transport was reduced in delta8-sterol-accumulating samples, due to an altered H+/ATP stoichiometry. ATP hydrolytic activity was increased, but no direct correlation with the extent or type of abnormal sterol accumulated could be drawn. Finally, Western...

Peroxisomes are ubiquitous organelles which participate in a variety of essential biochemical pathways. An intimate interrelationship between peroxisomes and mitochondria is emerging in mammals, where both organelles cooperate in fatty acid β-oxidation and cellular lipid homeostasis. As mitochondrial fatty acid β-oxidation is lacking in yeast and plants, suitable genetically accessible model sy...

A homologue of the gene encoding the transcription factor Rim101 (PacC), involved in pH signal transduction in fungi, was identified in the pathogenic basidiomycete Ustilago maydis. The gene (RIM101) encodes a protein of 827 amino acid residues, which shows highest similarity to PacC proteins from Fusarium oxysporum and Aspergillus niger. The gene had the capacity to restore protease activity t...

The dependence of Protein Kinase A (PKA) activity on cAMP levels is an important facet of the dimorphic switch between budding and filamentous growth as well as for pathogenicity in some fungi. To better understand these processes in the pathogenic fungus Ustilago maydis, we characterized the structure and biochemical functions of two phosphodiesterase (PDE) genes. Phosphodiesterases are enzyme...

The regulation of cyclin-dependent kinase (CDK) activity through inhibitory phosphorylation seems to play an important role in the eukaryotic cell cycle. We have investigated the influence that inhibitory phosphorylation of the catalytic subunit of mitotic CDK has on cell growth and pathogenicity of the corn smut fungus Ustilago maydis. This model pathogen is worthy of attention since it is wel...

Sexual compatibility requires self vs. non-self recognition. Genetically, two compatibility or mating-type systems govern recognition in heterothallic basidiomycete fungi such as the edible and woodrotting mushrooms and the economically important rust and smut phytopathogens. A bipolar system is defined by a single genetic locus (MAT) that can have two or multiple alleles. A tetrapolar system h...