Microbial Genetics - Fungal Genomics Unit
This research group is trying to understand the molecular basis of how fungal transcription factors act to integrate environmental nutrient signals (nitrogen and carbon sources) to coordinate primary and secondary metabolism. Moreover, the group studies how such molecular networks influence nitrogen and carbon cycling processes in soil.
Leader: Univ.-Prof. Mag. Dr. Joseph Strauss
- Transcriptional Networks: To study the molecular genetic regulation and signal transduction of nitrogen assimilation in the model fungus Aspergillus nidulans
- Fungal Epigenetics: To understand the role of chromatin modifications in the regulation of fungal primary and secondary metabolism (nitrogen regulation and mycotoxin biosynthesis gene expression, respectively)
- Functional Fungal Biodiversity: To correlate fungal molecular physiology with biodiversity and their function in soil nitrogen and carbon cycling processes; their interdependence with bacterial functions
1) Filamentous fungi are known as competent assimilators of different organic and inorganic nitrogen sources and we have been deciphering during the last years the molecular details of gene regulation events governing the efficient assimilation of nitrate into fungal biomass. Together with our Spanish and UK collaborators, we have also been clarifying how nitrate utilization is integrated into the nitrogen metabolic network applying molecular genetic and genomic (transcriptomic) methods. The understanding of nitrogen assimilation processes in fungi not only provides interesting fundamental insights into the function of transcription factors but continues to evoke interest of plant physiologist working in nitrogen regulation. Unlike in fungi, no nitrate assimilation-specific transcriptional network has been identified in plants so far. This work is correlated with BOKU Area of Competence 5 (“Food-Nutrition-Health”), but has also relevance for the area renewable resources (Competence Areas 3 and 4).
2) The function of eukaryotic transcription factors is strongly influenced by the accessibility of the DNA coding for genes they target for either activation or repression. Our group is one of the few worldwide working on the influence of chromatin on filamentous fungal gene expression. We have established that one function of the wide-domain nitrogen regulator AreA is to recruit chromatin modification complexes involved in the unwinding of DNA from the underlying, blocking, histones, thereby making DNA in the specific region of nitrate assimilation genes more accessible to the pathway-specific transcription factors.
Using a variety of chromatin modification mutants, we recently detected that fungal secondary metabolism and the production of the cancerogenic mycotoxin sterigmatocystin (ST) in A.nidulans is under chromatin accessibility control. This upper-hierarchical level of regulation, also termed “epigenetic regulation”, has now been proposed by us to represent a general mechanism of silencing secondary metabolism genes during the phase of active growth (primary metabolism). This work is correlated with BOKU Area of Competence 5 (“Food-Nutrition-Health”).
3) Recent publications and textbooks document that the role of fungi in soil nitrogen cycling has been largely missed, or at least vastly underestimated in the past. It is certainly of general importance to understand the fungal role in these microbial processes better, also when considering the enormous losses of nitrogen fertilizers (nitrate leaching, NOx volatilization, etc.) in agricultural production systems. Based on our detailed molecular understanding of fungal nitrogen regulation, we started an intradisciplinary effort strongly collaborating with groups working in microbial ecology (Prof. Wagner, Dept. of Microbial Ecology, Vienna Unversity), chemical ecology (Prof. Wanek, Prof. Richter, Dept. Chemical Ecology, Vienna Unversity), and plant molecular physiology (Prof. von Wirén, Univ. of Hohenheim, D) to link microbial biodiversity (bacterial, fungal) with their respective functions in soil nutrient cycling. These collaborative projects are funded by the Vienna Science and Technology Fund WWTF as well as by the FWF under the special National Research Network (NFN) program. The WWT project started around 3 years ago, the FWF-NFN around one year ago. Both projects are now providing the first results (partially already published) how fungi are integrated in these nutrient cycling networks, which role they play there and how they interact with bacteria and plants. This work is correlated with BOKU Competence Area CA 5 (“Food-Nutrition-Health”), but has also relevance for the area renewable resources (CAs 3 and 4) due to the question of production and fertilizer efficiency.
Jin Woo Bok, Yazmid Reyes-Dominguez, Yi-Ming Chiang, Edyta Szewczyk, Ashley D. Davidson, James F. Sanchez, Hsien-Chun Lo, Kenji Watanabe, Berl R. Oakley, Clay C. C. Wang, Joseph Strauss and Nancy P. Keller (2009). Chromatin-level regulation of cryptic biosynthetic gene clusters in Aspergillus nidulans. Nature Chem. Biol. (in press)
Asjad Basheer, Harald Berger, Yazmid Reyes-Dominguez and Joseph Strauss (2009). A library-based method to rapidly analyze chromatin accessibility at multiple genomic regions.
Nucleic Acid Research 37:e42
Harald Berger, Asjad Basheer, Sandra Böck, Thomas Dalik, Friedrich Altmann, and Joseph Strauss (2008). Dissecting individual steps of nitrogen transcription factor cooperation in the Aspergillus nidulans nitrate cluster. Mol. Microbiol 69: 1385 -1398
Yazmid Reyes-Dominguez, Narendja, F., Berger, H., Gallmetzer, A., Fernandez, R., Garcia, I., Scazzocchio, C. and Strauss, J. (2008) Nucleosome positioning and histone H3-acetylation are independent processes in the Aspergillus nidulans prnD-prnB bidirectional promoter. Euk. Cell 7: 656-663
Andreas Bernreiter, Ana Ramon, Javier Fernández-Martínez, Harald Berger, Lidia Araújo-Bazan, Eduardo A. Espeso, Robert Pachlinger, Ingund Anderl , Claudio Scazzocchio and Joseph Strauss (2007). Nuclear export of the transcription factor NirA is a regulatory checkpoint for nitrate induction in Aspergillus nidulans. Mol.Cell.Biol. 27: 791-802
Harald Berger, Robert Pachlinger, Igor Morozov, Mark Caddick, Sabine Goller, Frank Narendja and Joseph Strauss (2006). The GATA factor AreA regulates localization and in vivo binding site occupancy of the nitrate specific transcriptional activator NirA. Mol. Microbiol. 59: 433-446
Elke Kainz, Andreas Gallmetzer, Christian Hatzl, Juergen H. Nett, Huijuan Li, Thorsten Schinko, Robert Pachlinger , Harald Berger, Tillmann Gerngross, Stefan Wildt and Joseph Strauss (2007). N-glycan modification in Aspergillus species. Appl. Environ. Microbiol 74:1076-1086
Mark X Caddick, Meriel G Jones, J. Martin van Tonder1, Hélène Le Cordier1,Frank Narendja, Joseph Strauss, and Igor Y Morozov (2006) Opposing signals differentially regulate transcript stability in Aspergillus nidulans. Mol.Microbiol. 62: 509–519
Robert Pachlinger, Rudolf Mitterbauer, Gerhard Adam and Joseph Strauss (2005). Metabolically independent and accurately adjustable Aspergillus sp. expression system. Appl. Environ. Microbiol 71: 672-678
M.Isabel Muro Pastor, Joseph Strauss, Ana Ramón and Claudio Scazzocchio (2004). A paradoxical mutant GATA factor. Eukaryot Cell 3:393-405
Gerhard Adam, DAGZ, BOKU, ViennaChristian Luschnig, DAGZ, BOKU, ViennaChristian Obinger, Dept. of Chemistry, BOKU, ViennaRudolf Krska, F. Bertiller, R. Schuhmacher; IFA Tulln, Center for Analytical ChemistryClemes Peterbauer, Food Science & TechnologyKatja Sterflinger, Biotechnology, Austrian Center of Biological Resources and Appl. Mycol.