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Sugars as Prodrugs: Exploiting Sugar Metabolism in Bacteria.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Sugars as Prodrugs: Exploiting Sugar Metabolism in Bacteria.
Author:	Boulanger, Erin Farrell.
Published:	Ann Arbor : ProQuest Dissertations & Theses, 2023
Description:	267 p.
Notes:	Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
Notes:	Advisor: Ahmer, Brian.
Contained By:	Dissertations Abstracts International85-03B.
Subject:	Microbiology.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30747456
ISBN:	9798380370615

Sugars as Prodrugs: Exploiting Sugar Metabolism in Bacteria.
Boulanger, Erin Farrell.

Sugars as Prodrugs: Exploiting Sugar Metabolism in Bacteria. - Ann Arbor : ProQuest Dissertations & Theses, 2023 - 267 p.

Source: Dissertations Abstracts International, Volume: 85-03, Section: B.

Thesis (Ph.D.)--The Ohio State University, 2023.

This item must not be sold to any third party vendors.

Antibiotic resistance is an urgent public health problem and is associated each year with over a million deaths worldwide. Strategies to limit antibiotic exposures as well as improved practices for infection prevention and containment have been successful in reducing the emergence and spread of antibiotic resistance. Despite these efforts, novel therapeutic strategies are needed. In this dissertation, we investigate the induction of sugar-phosphate toxicities as a novel therapeutic modality to selectively target microbial pathogens. We use Salmonella enterica serovar Typhimurium, as our model pathogen, due to its clinical relevance, tractable genetics, and well-developed mouse models for studying infection. It is also one of the most characterized microbes and many aspects of its physiology and pathogenesis are relevant to other pathogens of the Enterobacteriaceae family for which antibiotic resistance is of paramount concern [i.e., the Carbapenem-resistant Enterobacteriaceae (CRE) and extended spectrum beta-lactamase (ESBL)-producing pathogens].Here, we have assembled and characterized a collection of Salmonella mutants predicted to suffer sugar-phosphate toxicity due to the absence of targeted enzymes within a variety of sugar-utilization pathways. Elimination of these enzymes coupled with the provision of the appropriate sugar leads to the accumulation of toxic sugar-phosphate intermediates resulting in growth inhibition. These mutations serve as a proxy for small molecule inhibitors of those enzymes that would be used in real-world therapeutic applications. Of the seven mutants tested in vitro, five (galE, galT, rhaD, mtlD, and araD) mutants showed growth inhibition in addition to a fraB mutant reported in earlier work. All but the galT mutant were also attenuated in a mouse model of Salmonella-mediated gastroenteritis. While homologs of galE are widespread among bacteria and in humans, the araD, mtlD, rhaD, and fraB genes are rare in most phyla of bacteria and are not present in humans, thus rendering the encoded enzymes promising narrow-spectrum therapeutic targets.Following the successful identification of genes that cause sugar-phosphate toxicity when mutated, we designed and optimized a high-throughput screening (HTS) protocol to identify small molecule inhibitors of one of our sugar-phosphate targets, FraB. Of the 224,009 compounds screened at Harvard's ICCB-Longwood Facility, we identified three lead compounds whose activities against wild-type Salmonella, but not fra-deficient Salmonella, are reproducible and have been confirmed biochemically to inhibit the FraB enzyme. This work sets the precedent for additional HTS to identify inhibitors of other sugar-phosphate toxicity targets.In the concluding study of this dissertation, we began to generate hypotheses regarding the molecular mechanism(s) by which sugar-phosphates inhibit growth. We utilized transcriptomics to characterize the gene expression profiles of cells undergoing four different sugar-phosphate toxicities at two different timepoints. STRING and iModulon analyses of our differentially expressed genes supported our understanding for the biological context of these changes.Overall, the work completed in this dissertation establishes the foundation for exploiting sugar-phosphate toxicity as a novel therapeutic modality to employ against Salmonella and other high priority pathogens.

ISBN: 9798380370615Subjects--Topical Terms:

192943
Microbiology.
Subjects--Index Terms:

Salmonella

Sugars as Prodrugs: Exploiting Sugar Metabolism in Bacteria.
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500 $a Advisor: Ahmer, Brian.
502 $a Thesis (Ph.D.)--The Ohio State University, 2023.
506 $a This item must not be sold to any third party vendors.
520 $a Antibiotic resistance is an urgent public health problem and is associated each year with over a million deaths worldwide. Strategies to limit antibiotic exposures as well as improved practices for infection prevention and containment have been successful in reducing the emergence and spread of antibiotic resistance. Despite these efforts, novel therapeutic strategies are needed. In this dissertation, we investigate the induction of sugar-phosphate toxicities as a novel therapeutic modality to selectively target microbial pathogens. We use Salmonella enterica serovar Typhimurium, as our model pathogen, due to its clinical relevance, tractable genetics, and well-developed mouse models for studying infection. It is also one of the most characterized microbes and many aspects of its physiology and pathogenesis are relevant to other pathogens of the Enterobacteriaceae family for which antibiotic resistance is of paramount concern [i.e., the Carbapenem-resistant Enterobacteriaceae (CRE) and extended spectrum beta-lactamase (ESBL)-producing pathogens].Here, we have assembled and characterized a collection of Salmonella mutants predicted to suffer sugar-phosphate toxicity due to the absence of targeted enzymes within a variety of sugar-utilization pathways. Elimination of these enzymes coupled with the provision of the appropriate sugar leads to the accumulation of toxic sugar-phosphate intermediates resulting in growth inhibition. These mutations serve as a proxy for small molecule inhibitors of those enzymes that would be used in real-world therapeutic applications. Of the seven mutants tested in vitro, five (galE, galT, rhaD, mtlD, and araD) mutants showed growth inhibition in addition to a fraB mutant reported in earlier work. All but the galT mutant were also attenuated in a mouse model of Salmonella-mediated gastroenteritis. While homologs of galE are widespread among bacteria and in humans, the araD, mtlD, rhaD, and fraB genes are rare in most phyla of bacteria and are not present in humans, thus rendering the encoded enzymes promising narrow-spectrum therapeutic targets.Following the successful identification of genes that cause sugar-phosphate toxicity when mutated, we designed and optimized a high-throughput screening (HTS) protocol to identify small molecule inhibitors of one of our sugar-phosphate targets, FraB. Of the 224,009 compounds screened at Harvard's ICCB-Longwood Facility, we identified three lead compounds whose activities against wild-type Salmonella, but not fra-deficient Salmonella, are reproducible and have been confirmed biochemically to inhibit the FraB enzyme. This work sets the precedent for additional HTS to identify inhibitors of other sugar-phosphate toxicity targets.In the concluding study of this dissertation, we began to generate hypotheses regarding the molecular mechanism(s) by which sugar-phosphates inhibit growth. We utilized transcriptomics to characterize the gene expression profiles of cells undergoing four different sugar-phosphate toxicities at two different timepoints. STRING and iModulon analyses of our differentially expressed genes supported our understanding for the biological context of these changes.Overall, the work completed in this dissertation establishes the foundation for exploiting sugar-phosphate toxicity as a novel therapeutic modality to employ against Salmonella and other high priority pathogens.
590 $a School code: 0168.
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650 4 $a Biomedical engineering. $3 190330
650 4 $a Molecular biology. $3 188737
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653 $a Sugar-phosphate
653 $a Sugar metabolism
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