Graduation Date

Spring 5-10-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Programs

Bioinformatics & Systems Biology

First Advisor

Kenneth W. Bayles

MeSH Headings

Staphylococcus aureus, Gram-Positive Bacteria, Bacterial Proteins, Pyruvic Acid/metabolism, Membrane Transport Proteins/genetics, Membrane Transport Proteins/metabolism, Metabolic Networks and Pathways, Gene Expression Regulation, Bacterial, Whole Genome Sequencing, Mutagen

Abstract

S. aureus is a highly versatile bacteria that significantly impacts human health. It is a medically important pathogen with high metabolic versatility, which allows it to infect various niches within a host. Understanding the metabolic processes that govern its fitness, virulence, and versatility is crucial for developing new strategies to combat staphylococcal infections. Pyruvate, a key intermediate of central metabolism, plays a vital role as a carbon distribution point for oxidative metabolism, overflow metabolite production, and fatty acid and amino acid biosynthesis. Pyruvate metabolism is a critical determinant of bacterial fitness and viability, as it plays a pivotal role in maintaining cellular homeostasis and energy production under both aerobic and anaerobic conditions. Previous works have suggested the involvement of S. aureus LrgAB proteins and their homologs in plants and other bacteria in transporting by-products of carbohydrate metabolism. Earlier, our lab demonstrated the importance of lrgAB for utilizing pyruvate during oxygen-limited growth. However, the pyruvate transporters under aerobic growth had yet to be elucidated. To identify these pyruvate transporters, we used the toxic pyruvate analog, 3-fluoropyruvic acid (3-FP), and selected resistant colonies potentially containing mutations in pyruvate transporters. We confirmed 3-FP resistance by culturing these mutants in liquid media containing the toxic analog. Whole genome sequencing identified putative lactate permeases lctP and lldP as pyruvate transporters. Our findings suggest that lctP and lldP are high-affinity transporters, based on their importance in the uptake of pyruvate at low concentrations (500μM).

Comments

2025 Copyright, the authors

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Available for download on Thursday, March 25, 2027

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