Biosynthesis and secretion of bacterial siderophores

点击翻译按钮获取中文摘要

Protein-protein interactions have been shown to be essential for a number of cellular processes including respiration. If we can find out how to stop bacteria from growing in iron-limited conditions by disrupting protein-protein interactions, we may eventually be able to use this information to discover powerful new antibiotics to which bacteria do not have resistance. Ferric iron is an essential nutrient for most bacteria, but this element is very scarce in the extracellular environment. To obtain scarce yet essential iron, bacteria have developed an iron acquisition strategy that relies on molecules called siderophores. Bacteria synthesize siderophores in the cytoplasm and then secrete them in order to scavenge iron from their environment. To get ferric-siderophores back into the cell, Gram-negative bacteria rely on a network of proteins in the cell envelope to import ferric-siderophores so they can be used for metabolic processes. Although we now know quite a bit about how the proteins in the import network work together to bring ferric-siderophores into the bacterial cell, we still know very little about how proteins work together to make siderophores and secrete them out of the cell. We will characterize the proteins involved in the synthesis and secretion of the E. coli siderophore called enterobactin. By understanding how these proteins work together, we will gain fundamental knowledge that will help us to understand how pathogenic bacteria use siderophores as virulence factors to cause diseases in animals and plants. We want to know if the enterobactin synthesis and secretion proteins communicate with each other through a network of protein-protein interactions, similar to what has already been shown for the proteins involved in ferric-siderophore import. We will try to find out if and how these proteins interact in our controlled laboratory environment by using biophysical techniques. We will also try to solve the three-dimensional structures of these proteins so that we can learn more about the protein surfaces that may tell us how they fit together. Once we know how these proteins can fit together based on our laboratory techniques, we can introduce mutations into these proteins to try to disrupt their interactions in a cell.