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Biosynthetic Engineering and Molecular Regulation of Bioactive Natural Products in Lysobacter enzymogenes
Abstract
Microbial natural products are one of the best sources for production of novel antibiotics, anticancer agents and immunosuppressants. Due to the persistent evolution of drug-resistant pathogens, the identification of novel antibiotics is extremely important. Over the past decade, Lysobacter has emerged as a rich source of bioactive natural products. This dissertation describes the regulatory mechanism and metabolic engineering of a group of natural products from Lysobacter enzymogenes for the industrial and antimicrobial applications.In the first chapter, we give a short review of structure, regulatory mechanism, and pathway engineering of HSAF and analogs, a group of polycyclic tetramate macrolactams in Lysobacter. In chapter two, we report a biosynthetic route to unsaturated odd-carbon fatty dicarboxylic acid (FDCA) based upon genetic modification of the polyketide synthase-nonribosomal peptide synthetase (PKS-NRPS) gene within L. enzymogenes. The newly engineered strain produces the C7 FDCA, hepta-2,4-dienedioic acid, an odd-carbon diunsaturated dicarboxylic acid. The subsequent chapters are based on regulatory mechanism of HSAF biosynthesis. In chapter three, we revealed a rare function of a TetR family regulator, which controls 3-hydroxylation of HSAF biosynthesis. We deleted the gene encoding a LeTetR regulator and found that the LeTetR mutant produced very little HSAF and alteramides, while the 3-dehydroxide compounds were not significantly affected. We assayed the activity of an enzyme extract from E. coli by expressing the fatty acid hydroxylase gene (hsaf-sd) and showed that the enzyme could restore the production of HSAF and alteramides in the LeTetR mutant for 3-hydroxylation of HSAF biosynthesis. In chapter four, we investigated regulatory mechanism for the LeTetR-regulated HSAF biosynthesis. We discovered that LeTetR binds to hsaf-sd gene encoding 3-hydroxylase. We have also determined that ligand binding to LeTetR affects its binding to the hsaf-sd gene which could ultimately 3-hydroxylation step of HSAF biosynthesis.
Subject Area
Biomedical engineering|Biochemistry|Molecular biology|Microbiology|Genetics
Recommended Citation
Khetrapal, Vimmy, "Biosynthetic Engineering and Molecular Regulation of Bioactive Natural Products in Lysobacter enzymogenes" (2022). ETD collection for University of Nebraska-Lincoln. AAI29168480.
https://digitalcommons.unl.edu/dissertations/AAI29168480