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Abstract
Vitamin B6 is an essential micronutrient for many biological processes in all three domains of life. Among the six B6 vitamers, pyridoxal 5′-phosphate (PLP) plays an irreplaceable role in cellular functions as a universal and versatile cofactor. Pathways involving PLP-dependent enzymes permeate the metabolic network, making studying vitamin B6 a powerful tool to probe the complexity of microbial physiology and metabolism. The research described herein seeks to expand our current knowledge on vitamin B6 biosynthesis, salvage, and homeostasis using Salmonella enterica serovar Typhimurium as a model organism. The first study investigates the unique ability of S. enterica to salvage phosphorylated B6 vitamers and identifies the enzyme responsible for this process. The next study examines the adverse effects of 4-deoxypyridoxine and uncovers a metabolic connection between vitamin B6 metabolism and synthesis of thiamine and coenzyme A. The last two studies explore the phenotypic and metabolic consequences caused by a mutation in yggS, which encodes a PLP-binding protein of unknown function, with a focus on vitamin B6 homeostasis and aspartate biosynthesis.