Role of acyl carrier protein in bacterial growth and pathogenesis

This proposal is focussed on acyl carrier protein (ACP), a small protein with a big role in bacterial growth and pathogenesis. Fatty acids are the building blocks of many bacterial components (eg. membrane lipids, endotoxin), and all fatty acids are attached to ACP during their synthesis and transfer to many enzymes involved in building complex lipids. Due to fundamental differences between bacteria and humans, these ACP-dependent enzymes are excellent targets for discovery of new anti-bacterial drugs: an urgent health need given increasing resistance of many pathogenic bacteria to existing antibiotics! Our primary approach is to engineer specific mutations (targetted amino acid replacements) in a bacterial ACP gene, then purify the protein and examine the role that each amino acid has on ACP structure and its ability to interact with individual enzymes. The main enzymes of interest in this proposal are involved in the synthesis of lipid A or endotoxin (responsible for septic shock) and small signalling molecules (AHLs) that bacteria use to regulate pathogenesis in a process known as quorum sensing. We also use mass spectrometry (proteomics) to identify which proteins interact with ACP in extracts of pathogenic bacteria such as Escherichia coli (foodborne illness such as diarrhea and "hamburger disease") and Helicobacter pylori (ulcers and gastric cancer).