Fungi inhabit complex environments and interact with plants, animals, and other microorganisms. To thrive in these environments, they must perceive external signals, process information, and adapt their growth and behaviour to the respective context. We aim to understand how fungi shape these interactions at the molecular level and whether pathogenic and mutualistic relationships rely on common underlying principles.

To address these questions, we combine experimental and computational structural biology with protein biochemistry, fungal genetics, cell biology, and functional signalling assays. Our research focuses on two complementary groups of molecules: membrane-embedded receptors that allow fungi to perceive signals, and secreted proteins through which they influence host or partner organisms.

Our central research questions are:

1. How do fungal receptors recognize signals originating from the environment or other organisms?
2. How are these signals translated into specific cellular responses?
3. How do secreted fungal proteins alter the physiology of host and partner organisms?
4. Which molecular principles are shared between pathogenic and symbiotic interactions?

We are associated with CEPLAS, the CRC1208 and part of CRC1535

More information can be found on our external webpage. 

G protein-coupled receptors are central interfaces between extracellular signals and intracellular responses. Although GPCRs control fungal growth, development, mating, and virulence, their ligands, structures, and activation mechanisms remain unknown for most fungal receptors.

We identify fungal GPCRs using structure-based and comparative approaches and investigate how many structurally and functionally distinct receptor classes exist in fungi. We then connect individual receptors to their ligands, activation mechanisms, G-protein partners, and biological functions. To achieve this, we combine structural predictions and cryo-electron microscopy with protein biochemistry, biosensor assays, and genetic analyses in fungi.

One example is the Gpe1–Pit2 system that we identified in the maize pathogen Ustilago maydis. During plant infection, a peptide signal is released from the secreted fungal protein Pit2 and activates the GPCR Gpe1. The fungus thereby exploits host-dependent processing to sense its entry into plant tissue and coordinate its subsequent growth. This system illustrates how effector biology and receptor-mediated signalling can be closely interconnected.

In addition to GPCRs, we investigate other membrane-associated proteins and intracellular components involved in signal perception and processing during pathogenic development.

Plant-pathogenic fungi secrete numerous proteins that suppress plant immune responses, alter metabolic pathways, or manipulate other central processes of their hosts. Many of these effector proteins are evolutionarily highly specialized and show little or no similarity to functionally characterized proteins. Their mechanisms of action can therefore often only be deciphered by combining structural, biochemical, and genetic approaches.

We determine the structures of selected effector proteins, identify their plant targets, and investigate their functions during infection. Using Ustilago maydis and related smut fungi as model systems, we examine how effectors interfere with plant immunity and hormone signalling and how new molecular functions emerge during the coevolution of fungi and their hosts.

Lichens are complex and spatially organized microbial communities. A fungal mycobiont forms a close association with a photosynthetically active algal or cyanobacterial partner and additional microorganisms. Together, these partners can colonize habitats that would be difficult for the individual organisms to inhabit on their own.

Using Peltigera lichens as a model system, we investigate how the mycobiont recognizes its partners, establishes the spatial organization of the lichen thallus, and controls the composition of the microbial community. We are particularly interested in membrane-embedded receptors, carbohydrate-binding proteins, and antimicrobial proteins. These molecules may facilitate close cellular contacts and enable the selective promotion or inhibition of different microorganisms.

By combining comparative genomics, spatial transcriptomics, protein biochemistry, and functional analyses, we aim to uncover fundamental principles underlying the establishment of stable mutualistic communities. At the same time, we ask whether symbiotic and pathogenic fungi employ related molecular strategies to perceive and influence their interaction partners.

^#shared correspondence

V. Joisten-Rosenthal, T. Arslan, M. Heinen, C. Kelly, Y. Sato, D. Garfias-Gallegos, L. Hüttebräucker, S. Robertz, V. Ramírez, J. Hecht, F. J. Pérez-Llanos, C. Pardo De la Hoz, J. Miadlikowska, X. Zhou, D. Joisten, J. P. Buchmann, M. Schmidt, J. Almer, R. F. Reynisson, S. Werth, P. Nakonz, M. Feldbrügge, M. Pauly, F. Lutzoni, B. P. H. J. Thomma, F. Altegoer, B. Usadel (2026) A chromosome-scale super-pangenome of the lichen genus Peltigera reveals genome architecture and expanded interaction repertoires shared across pathogenic and mutualistic fungi. bioRxiv

doi

G. Mendoza-Rojas, P. Nakonz, M. Lu, J. Postma, N. Shtakser, M. Heinen, M. Patel, O. Arguello-Miranda, S. Billerbeck, F. Altegoer (2025) A co-evolved peptide-GPCR system senses host entry to drive fungal infection. bioRxiv

doi

M. Heinen, H. Rövenich, F. Altegoer (2025) The Rise of fungal G-Protein Coupled Receptors in Pathogenesis and Symbiosis. PLoS Path. 

doi

S. Gul, G. Mendoza-Rojas, N. Heßler, S. Galle, S. H.J. Smits, F. Altegoer^#, V. Göhre^# (2025) Jasmonic acid signalling is targeted by a smut fungal Tin2-fold effector. J. Exp. Bot.

doi

Weiland P., Dempwolff F., Steinchen W., Freibert S.A., Tian H., Glatter T., Martin R., Thomma, B.P.H.J., Bange G.^#, Altegoer F.^# (2023) Structural and functional analysis of the cerato-platanin-like effector protein Cpl1 suggests diverging functions in smut fungi. Mol Plant Pathol.

doi

Han, X., Altegoer, F., Steinchen, W., Binnebesel, L., Schuhmacher, J., Glatter, T., Giammarinaro, P. I., Djamei, A., Rensing, S. A., Reissmann, S., Kahmann, R., & Bange, G. (2019). A kiwellin disarms the metabolic activity of a secreted fungal virulence factor. Nature, 565, 650-653.

doi

Full List | Google Scholar | Pubmed