Name: Dr. Dina Grohmann
Institution: Universitat Regensburg
Location: Regensburg, Germany
Tell me a bit about how you came to be interested in Archaea and what your work entails.
During my studies, I unfortunately never heard of Archaea. But when I was looking for a PostDoc position, I was lucky enough to meet Finn Werner (University College London) who was working on archaeal transcription. I was fascinated by the possibility to reconstitute the archaeal RNA polymerase and to be able to manipulate this enzyme to unravel the inner workings of such complex molecular machinery. So I joined his lab and I am hooked on archaeal research ever since. I am simply stunned by the diversity and fantastic inventions in the archaeal domain of life that were discovered over time. My research still focusses on the similarities and difference in archaeal-eukaryotic transcription machineries. But over the last years my lab also studies the machineries of antiviral defence in Archaea including a thorough investigation of the archaeal Argonaute protein.
We find that optical single-molecule microscopy and spectroscopy is an excellent to disentangle the structure-function-dynamics relationship of complex molecular machines and employ this technique frequently to follow conformational changes and to determine three-dimensional structures of proteins and protein-nucleic acid complexes. In 2015 I joined the University of Regensburg and am currently heading the well-known German Archaea Centre, which was founded by Karl Stetter, one of the pioneers and most distinguished researchers in the archaeal research field. Karl Stetter “hunted”, cultivated and described numerous archaeal organisms and ever since, Regensburg is home to the Archaea collection. We are fully equipped to cultivate the most extreme archaeal species making it “archaeal research heaven”. Being located in Regensburg now allows me to expand my research to include in vivo investigations and to discuss archaeal research with the many archaeal experts in Regensburg (who also kindly contributed their views to the questions in this interview).
Archaeal experts in Regensburg
The image shows an artistic interpretation of an archaeal defence mechanism against foreign nucleic acids mediated by the Argonaute protein from Methanocaldococcus jannaschii (for details see studies by Zander et al and Willkomm et al in Nature Microbiology, 2017). We gratefully acknowledge the support of Katharina Auguste Liphardt-Willkomm in creating this artistic interpretation. Scanning electron microscope image of a M. jannaschii cell is courtesy of G. Wanner ( LMU Munich).
Looking back at the last 40 years, what would you describe as the most exciting areas of research linked to the study of the Archaea? And where do you see the field headed in the next decade?
After Woese and Fox put forward the idea about the third domain of life, I think one of the most significant discoveries in the beginning was that Archaea do not encode an RNA polymerase comparable to the bacterial counterpart but that archaeal RNA polymerases are most akin to the eukaryotic RNA polymerase II. This did not only strongly support the notion that Archaea constitute a separate phylogenetic domain and differ significantly from their prokaryotic siblings, the Bacteria; it also provided us with an excellent model system to study the molecular mechanisms of archaeal-eukaryotic transcription as – in contrast to the eukaryotic transcription machinery - the archaeal RNA polymerase and respective transcription complexes can be reconstituted and dissected in vitro. These studies provided unprecedented insights into the working of one of the most fundamental machineries in life. Other exciting discoveries in archaeal research changed our view of biological life in general. Here I will name a few of the most intriguing findings: i) the discovery of the smallest living cell on earth, which happened to be an archaeal organism (Nanoarchaeum equitans) that lives in a unique symbiosis with a archaeal host (Ignicoccus hospitalis), ii) the discovery that Archaea use a unique motor for swimming (archaeal flagella/archaella) that is not comparable to the bacterial flagella, iii) the discovery of methanogenesis as a metabolic pathway only employed by Archaea, iv) the description of a living cell that cannot only withstand but also grow at temperatures beyond the boiling point of water, v) the discovery of bacteriorhodopsin and vi) the very recent discovery of the ASGARD Archaea as the closest relatives of eukaryotic cells.
In my opinion, we still have to learn a lot about how archaeal cells communicate with each other and with bacteria when sharing a biotope, e.g. in biofilms and as part of our microbiome. With the advent of metagenomics analysis, we are now in the fantastic situation to discover new archaeal lineages and to describe complex archaeal-bacterial communities even if Archaea represent only a small fraction in this biotope. With the new exciting possibilities of cryo-electron tomography, we also will be able to directly “look” into archaeal cells with unprecedented spatial resolution. Hopefully, members of the ASGARD Archaea will be cultivated soon in order to be able to answer all the pressing questions about the evolution of complex eukaryotic cells. There is also a lot to learn about the life of mesophilic archaea and their role in the global nitrogen and carbon cycle. Another question concerns the distribution of Archaea not only on Earth but also on other planets. Perhaps we will detect archaeal life forms on other planets. But we also have to think about ways to prevent contamination of planets during planetary exploration as Archaea are extremely resistant against radiation and heat they might be able to travel with spaceships.
What would you like the public (and general microbiological audience) to appreciate about Archaea?
Archaea have adapted to live even under extreme environmental conditions and therefore, they can be considered to be the superheroes of the microbial world. Studying Archaea helps us to understand the evolution of life. However, while Archaea are mostly recognised as extremophiles that conquered inhabitable places on our earth, they are not rare species. They are also part of our microbiome and interact with us. And even though there is no pathogenic archaeal organism known thus far, Archaea greatly influence our life and contribute to our wellbeing in many ways.
Are there any particular papers that you feel are absolute must reads for those that aren’t necessarily familiar with the field (and briefly, why)?
Huber, H. et al. A new phylum of Archaea represented by a nanosized hyperthermophilic symbiont. Nature 417(6884):63-7 (2002).
Discovery of the smallest living organism on planet earth and description of the first archaeal symbiosis.
Stetter, K. History of discovery of the first hyperthermophiles. Extremophiles. 10:357–362 (2006).
A journey back in time that describes the isolation and cultivation of extremophilic Archaea including Archaea that can grow above the boiling point of water. The author, Karl Stetter, is a pioneer in archaeal research and hunted and describes countless archaeal organisms.