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Genomic Approach to Uncover the Nitric Oxide Response Network In Escherichia Coli

Katherine J. Chou and James C. Liao. Chemical & Biomolecular Engineering, University of California, Los Angeles, 5531 Boelter Hall, 420 Westwood Plaza, Los Angeles, CA 90095

Nitric oxide (NO) is a versatile signaling molecule in both mammalian and microbial systems. It is utilized by mammalian immune response to combat microbial invasion. To counter the NO effect, microorganisms have complex intracellular defense networks to detoxify NO. We have previously shown that under aerobic condition in minimal media, NO damages iron-sulfur protein dihydroxy acid dehydrotase (IlvD). This perturbation disrupts the biosynthesis of branch-chain amino acids and leads to E. coli bacteriostasis. However, the intracellular networks that render resistance to NO remain partially understood due to the complexity of NO chemistry, metabolism, and transport. Using a genomic approach, we systematically mapped the NO response network which confers NO-resistance in E. coli. This network involves many unknown or uncharacterized genes, which highlights the power of this approach for investigating networks beyond the well characterized genes.