Regulation of Swarming Motility by Polyamines in Escherichia Coli and Enzymatic Assay of D-Mannose from Urine




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Swarming is a type of surface motility behavior exhibited by a few bacterial families. Polyamines are aliphatic cations known to modulate protein synthesis and impact gene expression and we studied the role of these polyamines in modulating swarming in Escherichia coli. There are nine enzymes that synthesize polyamines (putrescine, spermidine and cadaverine) in E. coli. Chapter 2 describes the requirement of putrescine in regulating swarming motility in E.coli. Analysis of different genetic knockouts in the polyamine anabolic pathways showed that putrescine, but not spermidine, is important for swarming. Putrescine transport and catabolism were also shown to be critical for this type of surface movement behavior. Evidence is presented that suggests that one function of putrescine is to provide resistance to oxidative stress during swarming. Urinary tract infections are one of the most common bacterial infections in humans. Many studies show that D-mannose ingestion diminishes the frequency of urinary tract infections, perhaps by blocking the binding of pathogenic bacteria to the bladder epithelium. We want to test whether women susceptible to urinary tract infections have low urinary D-mannose, and whether oral D-mannose increases urinary D-mannose. However, there is no published technique to specifically and sensitively measure D-mannose in urine. I developed a reliable, precise, sensitive, and fast enzymatic method to measure D mannosuria in women, and this assay is described in Chapter 3. This reliable method of measuring D-mannosuria may prove useful to determine the efficacy and optimize the intake (dose, intake frequency, elimination ratio) of Dmannose in women suffering from recurrent urinary tract infections. Chapter 4 discusses the results from a published article where it is shown that CyuA is a major anaerobic cysteine catabolism enzyme in both E. coli and S. enterica. My contribution was to examine regulation of cyuA in E. coli. In this paper, we presented evidence that CyuA was present in the Last Universal Common Ancestor (LUCA).



Polyamines, Bacteria—Motility, Escherichia coli, Putrescine, Urinary tract infections