Functional analysis of stress-dependent RNA-enzyme interactions

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Cells have to immediately respond to changing environmental conditions. In particular, unicellular organisms such as baker's yeast Saccharomyces cerevisae must immediately react to cope with an altered environment. Since yeast is also important for production of food, wine and other goods, there is great interest to understand how the cells can deal with stress to optimise industrial applications. Specifically, the response to oxidative stress, which is imposed by the imbalance in the levels of so-called reactive oxygen species (ROS) generated during normal aerobic metabolism but particularly through exposure to certain toxic chemicals or irradiation, is of wider interest because it is connected to the development of diverse pathological processes in humans, such as neurodegenerative disorders, diabetes, arthritis and cancer. Cells have developed a variety of mechanisms to adapt to stress, including immediate changes in the levels of key metabolites and by altering gene expression. Regarding the latter, it has become particularly recognised that stress response is considerably affecting the synthesis of new proteins, and the stability of RNAs. RNA represents an essential intermediate step in gene expression, where DNA is copied into RNA to serve as template for protein synthesis. Importantly, RNA is never naked in cells but covered by a host of proteins, so-called RNA-binding proteins (RBPs). These proteins can remove or rearrange parts of RNA, store, or deliver it to particular locations within the cell, and ultimately degrade it. They also control when and how messenger RNAs (mRNAs; refers to the class of RNAs that encode proteins) are translated into proteins. Due to the tremendous importance of RPPs in gene expression control, we and other researchers have developed an experimental approach to catalogue all of the RBPs that interact with mRNAs in cells. Besides detecting many of the previously known RPBs, it was found that proteins with other well-established functions, such as enzymes, could interact with mRNAs (enzymes are proteins that perform essential chemical reactions in the cell). Furthermore, we have investigated which RBPs change mRNA associations upon oxidative stress in yeast. Interestingly, we found that many of the ones that changed mRNA associations were metabolic enzymes acting in carbon metabolisms, which is central for energy production and storage in cells; and provides building blocks for the synthesis of complex biological molecules. Therefore, we wish to understand the function of these "enigmatic" enzyme-RNA interactions and whether they could play a role in coping with oxidative stress. We will first test whether the observed changes in RNA-enzyme interactions are specific to oxidative stress or apply to other stress conditions as well. We will then comprehensively identify the RNA targets for selected enzymes acting in central carbon metabolisms, and investigate where and how they bind to RNAs. Finally, we wish to explore whether the stress-dependent interactions with RNA affects their fate, or conversely, whether it modulates enzymatic activity and plays a role in the cell's adaptation to stress. With our research, we expect to discover previously unrecognised links between RNA regulation, metabolism and cellular stress response. If so, this knowledge will likely have impact on diverse important aspects of our society, from food-production towards a better understanding of components that contribute to today's most prominent diseases including cancer.