Regulation of the Snf1 Protein Kinase in Yeast

University Of Wisconsin-Milwaukee, Milwaukee WI

Investigators

Abstract

a. Abstract The ability to adapt to stress is one of the main characteristics of life. The molecular mechanisms by which such adaptation is achieved are of fundamental interest to modern biology. It is increasingly clear that stress tolerance is coupled to the cell's ability to be a good shepherd of its resources. The vital importance of molecular resource-managing systems is reflected in the remarkable evolutionary conservation of their key regulatory components. Members of the Snf1/AMP-activated protein kinase (AMPK) family are found in eukaryotes as complex as mammals and as simple as yeast. Mammalian AMPK is activated in response to energy limitation (increased cellular AMP-to-ATP ratios), and functions to restore the energy balance by stimulating ATP generation and inhibiting ATP consumption. Snf1 protein kinase of budding yeast (Saccharomyces cerevisiae) becomes activated and promotes the utilization of alternative carbon/energy sources when the preferred source, glucose, becomes limiting. In addition to glucose limitation, Snf1 has been implicated in responses to various other stress conditions. Due to advantages offered by the yeast system, studies of Snf1 have been providing invaluable insights into the most fundamental aspects of Snf1/AMPK structure and function. However, many questions still remain unanswered. It is known that Snf1 is activated by partially redundant upstream kinases (Sak1, Tos3, and Elm1) and inhibited by the Reg1-Glc7 phosphatase, but the exact mechanisms that shift the balance between these opposing processes remain unknown. To gain further knowledge, an innovative genetic screen for mutants with defects in the Snf1 pathway has been devised and performed. This project uses genetic, molecular, and biochemical methods to determine how the novel regulators thus identified interface with the known elements of the Snf1 pathway, and how they deliver signals from other sensory systems of the cell. This research will advance our understanding of the Snf1/AMPK family and its functions, general mechanisms of protein kinase regulation, and mechanisms of stress tolerance in eukaryotes. The results obtained will be of general interest to the scientific community. Broader impacts: Graduate and undergraduate students, including women and minorities, will participate in this project, and will receive excellent training to pursue their careers in research and science education. Experiments from this work will be incorporated into an experimental microbiology course for graduate and undergraduate students. The results obtained will be used to constantly update an advanced graduate course on signal transduction. Because Snf1-related kinases are involved in stress responses in plants, this work also has the potential to suggest new approaches to improving agricultural practices.