Molecules present in the outer membranes of cells act as antennae to perceive changes in the environment, and transmit this information into the cell by chemical reactions (for example phosphorylation) and by changes in shape (or conformation.) Newly developed technologies allow such conformational changes in molecules to be detected using the methods of mass spectrometry, and in this project these new technologies will be used to understand how signals regulate the rapid expansion of plant cell size. Exercises will be developed for high school students, using mass spectrometry to analyze common food proteins such as soybean tofu. A PBS television series "Wednesday Nite at the Lab" that is broadcast free from the University of Wisconsin Biotechnology Center will explain to the general public (and demystify) mass spectrometry, using as an example the analysis of plant proteins and explaining how this impacts their everyday lives.
Overall this project seeks to combine in vitro and in vivo approaches to understanding the molecular basis for signal transmission across the plasma membrane. The focus of this project is Feronia, a plant plasma membrane receptor kinase, and its peptide hormone ligand, RALF. When RALF binds to the extracellular domain of Feronia, the rate of cell expansion is reduced within minutes. This project will develop and apply novel mass spectrometric based tools for analyzing the conformational changes that extracellular RALF induces in Feronia. The newly devised PLIMB instrument (Plasma Induced Modification of Biomolecules) that generates microsecond pulses of hydroxyl radicals will be used to "footprint" Feronia and other proteins that are involved in Feronia/RALF action at the plasma membrane.
