Mechanism, Structure, and Inhibition of N-Monooxygenases

Many pathogenic bacteria and fungi require iron from the host to establish infection. A deep understanding of iron acquisition mechanisms is crucial for unraveling the principles of pathogenicity and could lead to innovative drug design strategies to tackle antibiotic resistance. One key aspect of iron acquisition is the secretion of low- molecular-weight, iron-scavenging molecules known as siderophores. This project focuses on investigating enzymes that catalyze a critical step in the biosynthesis of hydroxamate-containing siderophores. Flavin-dependent N-monooxygenases play a central role in this process by introducing hydroxyl groups onto the amino acid building blocks of siderophores, which ultimately contribute to the iron-chelating hydroxamate functional groups in the mature siderophore. These enzymes are essential for virulence in pathogenic organisms such as the fungus Aspergillus fumigatus and bacteria like Acinetobacter baumannii. This foundational study establishes a framework for investigating the structure, catalytic mechanism, and inhibition of flavin-dependent N-monooxygenases. In this proposal, we aim to: (1) perform detailed biochemical and structural studies of histamine N-monooxygenases from pathogenic bacteria, (2) identify and characterize inhibitors of the ornithine N-monooxygenase from A. fumigatus (SidA), and (3) structurally characterize elusive intermediates in the reaction catalyzed by SidA. The project will serve as an excellent platform for training undergraduate students in protein chemistry, enzyme characterization, inhibitor design and validation, and structural biochemistry. The successful completion of these aims will enhance our understanding of the molecular basis of siderophore- mediated iron assimilation and generate lead compounds for future drug development. Project Number: 1R15GM164647-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of General Medical Sciences (NIGMS) | Principal Investigator: Pablo Sobrado | Institution: MISSOURI UNIVERSITY OF SCIENCE & TECHNOLOGY, ROLLA, MO | Award Amount: $528,560 | Activity Code: R15 | Study Section: Macromolecular Structure and Function A Study Section[MSFA] View on NIH RePORTER: https://reporter.nih.gov/project-details/11349396