The structure, mechanism of action and copper stoichiometry of the transmembrane sensor domain of the plant ethylene receptor ETR1 and homologs have remained elusive, hampering the understanding on how the perception of the plant hormone ethylene is transformed into a downstream signal. We generated the first structural model of the transmembrane sensor domain of ETR1 by integrating ab initio structure prediction and coevolutionary information. To refine and independently validate the model, we determined protein-related copper stoichiometries on purified receptor preparations and explored the helix arrangement by tryptophan scanning mutagenesis. All-atom molecular dynamics simulations of the dimeric model reveal how ethylene can bind proximal to the copper ions in the receptor, illustrating the initial stages of the ethylene perception process.

Orthologous proteins do not necessarily share the same function in all species and those sharing the same function might employ a modified catalytic mechanism. Thus, comparative analysis of homologous or orthologous proteins from different organisms can provide detailed information on the function and the mechanism of an entire protein family. The sensor kinase ETR1 from Arabidopsis thaliana has been well characterized by genetic, physiological and biochemical studies. However, as further model plants are coming into focus for plant hormone research, a general protocol for isolation and purification of orthologous ETR1 proteins seems instrumental for a detailed molecular analysis of this protein family. In this study, we describe the native purification of recombinant ETR1 from Arabidopsis thaliana by mild solubilization with the zwitter-ionic detergent Fos-Choline-14 and single-step purification by immobilized metal ion affinity chromatography. The same protocol was successfully applied for the purification of the orthologous proteins from the moss Physcomitrella patens subsp. patens and the tomato Lycopersicon esculentum. The successful transfer of the purification protocol to proteins of the same family which share sequence identity of 63-80% only suggests that this protocol presents a general purification strategy which is likely to apply also to the purification of other members of the sensor histidine kinase family.

Protecting our water resources in terms of quality and quantity is considered one of the big challenges of the twenty-first century, which requires global and multidisciplinary solutions. A specific threat to water resources, in particular, is the increased occurrence and frequency of flood events due to climate change which has significant environmental and socioeconomic impacts. In addition to climate change, flooding (or subsequent erosion and run-off) may be exacerbated by, or result from, land use activities, obstruction of waterways, or urbanization of floodplains, as well as mining and other anthropogenic activities that alter natural flow regimes. Climate change and other anthropogenic induced flood events threaten the quantity of water as well as the quality of ecosystems and associated aquatic life. The quality of water can be significantly reduced through the unintentional distribution of pollutants, damage of infrastructure, and distribution of sediments and suspended materials during flood events. To understand and predict how flood events and associated distribution of pollutants may impact ecosystem and human health, as well as infrastructure, large-scale interdisciplinary collaborative efforts are required, which involve ecotoxicologists, hydrologists, chemists, geoscientists, water engineers, and socioeconomists. The research network “project house water” consists of a number of experts from a wide range of disciplines and was established to improve our current understanding of flood events and associated societal and environmental impacts. The concept of project house and similar seed fund and boost fund projects was established by the RWTH Aachen University within the framework of the German excellence initiative with support of the German research foundation (DFG) to promote and fund interdisciplinary research projects and provide a platform for scientists to collaborate on innovative, challenging research. Project house water consists of six proof-of-concept studies in very diverse and interdisciplinary areas of research (ecotoxicology, water, and chemical process engineering, geography, sociology, economy). The goal is to promote and foster high-quality research in the areas of water research and flood-risk assessments that combine and build off-laboratory experiments with modeling, monitoring, and surveys, as well as the use of applied methods and techniques across a variety of disciplines.

Water is an essential element and highly valuable resource in life. Between the priorities of environment, people and economy, it is of increasing importance to fully understand the fundamental force of water to be capable of handling waterborne events—such as flooding—manage and ensure water quality and availability, and utilize hydraulic energy. The Institute of Hydraulic Engineering and Water Resources Management (IWW) at RWTH Aachen University has a long research tradition in this field. Going back to the founding year of the university in 1870, the chair is based on the work of civil engineer Otto Intze, who is best known for his pioneering contributions in construction of dams and elevated water tanks. Ever since then, the institute has broadened its research spectrum and is today focusing on flood protection structures, hydraulic engineering design, integrated coastal zone management, morphodynamics and ethohydraulics. In a comprehensive approach, physical model experiments are combined with field measurements and numerical simulations to investigate a wide range of projects. With its annually organized International Symposium on Hydraulic Engineering (IWASA), the institute also offers information to a wide audience on highly topical aspects in the field of water engineering works and water management, while at the same time bridging the gap between science and industry. The institute is part of the “Project House Water”, a research network at RWTH Aachen University that was established within the framework of the German excellence initiative. Here, scientific competencies from the fields of ecotoxicology, process engineering, geography, sociology, economy and hydraulic engineering are focussed to allow for an interdisciplinary, holistic assessment of flooding events and their impacts.