Pumping life Oleg Sitsel,ph.d. student, Ingrid Dach, ph.d. student and Robert Hoffmann, ph.d. student, PUMPKIN, Department of Molecular Biology and Genetics, Aarhus University, Science Park and Dept. of Plant Biology and Biotechnology, Faculty of Life Sciences, University of Copenhagen. [email protected], ingrid@biophys. au.dk, [email protected] The name PUMPKIN may suggest a research cen- clinically important drug targets e.g. in the treat- tre focused on American Halloween traditions ment of congestive heart failure or gastric ulcers, or the investigation of the growth of vegetables and they encompass promising targets for a broad – however this would be misleading. Research- range of novel drugs. ers at PUMPKIN, short for Centre for Membrane Pumps in Cells and Disease, are in fact interested Research at the PUMPKIN centre is highly inter- in a large family of membrane proteins: P-type disciplinary, making use of the knowledge, exper- ATPase pumps. This article takes the reader on a tise and equipment from many groups spanning tour from Aarhus to Copenhagen, from bacteria over a number of institutions. P-type pumps are to plants and humans, and from ions over protein therefore studied from different perspectives, structures to diseases caused by malfunctioning starting with basic research on their structure and pump proteins. The magazineNature once titled function and ending up transferring this knowl- work published from PUMPKIN ‘Pumping ions’. edge to biotechnology and drug discovery. This Here we illustrate that the pumping of ions means broad approach involves the use of a great variety nothing less than the pumping of life. of experimental techniques such as X-ray crystal- lography, biochemical studies, bioinformatics and “P-type ATPases are membrane pumps respon- cell biology. sible for the transport of various cations and lip- ids in all kingdoms of life and their proper func- A defining feature of research at the PUMPKIN tion is absolutely necessary for survival,” explains centre is a high level of collaboration and interac- Poul Nissen, director of the PUMPKIN centre that tion between different institutions and research- spreads over several departments at Aarhus Uni- ers with various backgrounds. But how can one versity and the University of Copenhagen. Poul manage to coordinate such a big research centre became interested in P-type ATPases when he spread over many different institutions? “The key returned back to Denmark from his postdoctoral to success here is the integrity and good chemistry stay at Yale University where he worked on unrav- among participants,” believes Poul. Everybody at eling the structure and function of the ribosome the centre can confirm that collaboration, open- in the laboratory of the 2009 Nobel Prize laureate ness and an extremely friendly atmosphere re- Thomas A. Steiz. “The main reason why I decided ally are the key defining features at PUMPKIN. All to focus on membrane pumps was the long-stand- international students and researchers are sur- ing research tradition of studying these proteins prised and impressed by this relaxed and friendly at both Aarhus and Copenhagen Universities, and approach, and maybe this is one of the reasons the fact that I could see great interesting projects why the environment at PUMPKIN has become lying in front of us,” says Poul. truly international and English is often spoken more frequently than Danish. “Research cultures The long and successful tradition of investigating membrane pumps in Denmark started when the first P-type ATPase - the sodium-potassium pump - was discovered at Aarhus University in 1957 by Jens Christian Skou, who was later awarded one half of the 1997 Nobel prize in Chemistry ‘for the first discovery of an ion-transporting enzyme’. In his preparation of finely ground crab nerve mem- branes, J.C. Skou identified a membrane pump that uses the energy derived from hydrolysis of ATP to maintain a stable difference in the concen- tration of potassium and sodium across biological membranes. Shortly after, other P-type ATPases and their crucial roles for all cells were identified and investigated. Because of their indispensable role in many life processes it is perhaps not sur- prising that many members of the P-type ATPase family have been implicated in the onset of vari- ous diseases. Consequently, P-type ATPases are Poul Nissen, director of the PUMPKIN centre Biokemisk Forening BioZoom 2 2012 | 7 The PUMPKIN logo, designed by Helene P. Brovang and Morten Kjeldgaard, expresses not only the sub- ject of interest of the centre but also its approaches and organization. Its four corners represent the four different states that a P-type ATPase pump repeatedly undergoes within its functional cycle (left) and also symbolize the interdisciplinary approach (middle) and cross-institutional organization (right) of PUMPKIN with a high level of collaboration and interaction; twisted angles are a symbol of a broader perspective of research that is ranging from detailed structures of pumps at an atomic level to their roles in human physio- logy of health and disease. of many countries are mixed and the best of each pump. Scientists from the centre published three contribution is exposed and grasped by others,” individual articles in a 2007 December issue of the describes Poul the international environment highly prestigious journal Nature (and earned the at PUMPKIN – and you can see he really enjoys front cover illustration!), describing fundamental leading a big international group. “International new insight on the structure and function of three students are often a great inspiration for others different P-type ATPases. All these structures, to- thanks to their enthusiasm to learn new things, gether with many mutational, biochemical and their curiosity and hard work attitude,” he adds. physiological studies that followed, allow re- And Poul evidently knows how to attract them searchers at PUMPKIN to gain more information – more than half on the young researchers (PhD about the functional cycle of these pumps, their students and postdocs) at PUMPKIN are foreign- important structural features and physiological ers, from countries as close as Germany, Sweden roles. And what are the goals and plans for PUMP- or the Baltics or as far away as China. “We always KIN’s bright future? “It would be great to have make sure that there are great projects with great crystal structures and functional studies for all questions that the students can identify with,” types of P-type ATPases,” says Poul. “At the same Poul explains. “And we never forget to focus on time we are now more and more interested in the education, talent development and career op- larger and more complex networks of pumps and portunities of our young participants.” their interaction partners where the vision is to get to a bigger picture integrating our knowledge One of the most important breakthroughs for the from structural biology, biochemistry, molecular PUMPKIN centre took place in 2007, not even one cell biology and physiology.” It looks like Danish year after its inauguration and exactly 50 years Universities will certainly keep their leading po- after J.C. Skou discovered the sodium-potassium sition in the field of P-type ATPase research that was initiated by J.C. Skou 55 years ago. The Green Branch of PUMPKIN Twenty-four years. That is the expertise Michael Palmgren has in research on proton pumping P- type ATPases from plants. Back in 1988 as PhD student at the University of Lund in Sweden, he published his first paper ‘Modulation of plasma- membrane H+-ATPase from oat roots by lysophos- phatidylcholine, free fatty-acids and phospho- lipase A2.’ Since then a lot has changed. On the personal side, Michael has become professor at the University of Copenhagen and a group leader at PUMPKIN. On the subject side, oat has been outcompeted by the model plant Arabidopsis thali- ana, and research is performed on various aspects of P-type ATPases. “The reason why we focus on plasma membrane proton ATPases,” Michael ex- plains, “is that they have been present in plants since plants evolved. They create a membrane potential which enables transport of other ions across the membrane. Proton transport is simply Michael Broberg Palmgren, leader of the PUMPKIN among the most important actions in plants.” branch in Copenhagen 8 | BioZoom 2 2012 Biokemisk Forening Researchers at PUMPKIN at the annual meeting in August 2011. Since its foundation, PUMPKIN conside- rably grew in size and consists now of 12 individual research groups that attract more and more students, postdocs and visiting scientists every year. Besides proton pumps, the research group works In a workplace where most people are between also on pumps called flippases. Flippases (a sub- 25 and 35 years old, announced pregnancies and family of P-type ATPases) are thought to trans- births are often celebrated. Merethe Mørch Frø- port lipids between the two leaflets of a biological sig is working on the regulation of flippases and membrane. This process would provide the start- is also a PhD-student at PUMPKIN. “I brought a ing point for vesicle formation, a process impor- big cake and fruits on the day I told my colleagues tant in endo- and exocytosis. about my pregnancy. Det var hyggeligt!” she smiles. Her project will not pause during the time How do the flippases and proton pumps function she takes maternity leave. “I’ve great colleagues at the atomic level? How are they regulated? What who will continue parts of my projects while I’m are their physiological roles? These questions drive on leave so that nothing is lying still. This is very Michael and 16 others at PUMPKIN in Copenha- important in an environment as dynamic as the gen. Alex Green Wielandt is one of them. He is at PUMPKIN centre.” the beginning of his 3 year PhD studies, and uses a technique where he introduces proton pumps into From basic science to business: Pcovery artificial lipid vesicles called liposomes.