Probing the Consequences of Irreversibly Trapping Iron in Bacterioferritin Using Chemical and Genetic Approaches--An Omics Study

Author

Leo S. Fontenot Jr., Louisiana State UniversityFollow

Degree

Doctor of Philosophy (PhD)

Department

Chemistry

Document Type

Dissertation

Abstract

Antibiotic resistant bacteria pose one of the most urgent threats to public health. Pseudomonas aeruginosa is a multi-drug resistant bacterium for which new antibiotics are urgently needed. My research is focused on understanding and validating iron metabolism as a target for antibiotic development by analyzing the metabolic profiles of iron-starved P. aeruginosa cells caused by irreversibly trapping iron in bacterioferritin. Iron is an essential nutrient for bacteria; however, the reactivity of the Fe²⁺ ion and insolubility of the Fe³⁺ ion present significant challenges to bacterial cells. Iron storage proteins oxidize Fe²⁺ using O₂ and H₂O₂ as electron acceptors to store Fe³⁺, thus relieving the bacteria of these challenges. The function of iron storage proteins was extensively investigated in Pseudomonas aeruginosa, a Gram-negative, multi-drug resistant opportunistic pathogen that affects immunocompromised individuals, burn victims, and cystic fibrosis patients. BfrB is the iron storage protein in P. aeruginosa, and the iron stored inside is mobilized, with the aid of bacterioferritin-associated ferrodoxin (Bfd), in late exponential and early stationary growth phases, when iron in the environment has been exhausted. Most importantly, inhibition of the BfrB-Bfd interaction in P. aeruginosa causes irreversible iron accumulation in BfrB and iron deficiency in the bacterial cytosol. Herein, we examine the global metabolic changes ensuing from iron starvation caused by the irreversible accumulation of iron in BfrB, which leads to iron limitation in the P. aeruginosa cytosol. Using proteomics and metabolomics-based approaches, it was found that inhibiting the BfrB-Bfd interaction causes differences in metabolites related to iron acquisition, amino acid, and energy metabolism. Likewise, the trapping of iron in bacterioferritin by a small molecule BfrB-Bfd inhibitor dysregulates metabolic homeostasis in the P. aeruginosa cell.

Date

10-30-2023

Recommended Citation

Fontenot, Leo S. Jr., "Probing the Consequences of Irreversibly Trapping Iron in Bacterioferritin Using Chemical and Genetic Approaches--An Omics Study" (2023). LSU Doctoral Dissertations. 6286.
https://repository.lsu.edu/gradschool_dissertations/6286

Committee Chair

Rivera, Mario