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Abstract
The Rid (YjgF/YER057c/UK114) protein superfamily is conserved in all domains of life and members of the family have been implicated in a myriad of metabolic processes. The physiological role and conserved biochemical activity of RidA (reactive intermediate deaminase), the archetypal member of the protein family, was demonstrated using biochemistry and genetics in Salmonella enterica. The RidA paradigm established in S. enterica, serves as a framework to study the integration of RidA into the metabolic networks of other organisms. Mutant phenotypes arise in multiple organisms, both eukaryotic and prokaryotic, that lack RidA and evidence suggests damage by the reactive metabolite 2-aminoacrylate (2AA) is responsible for these phenotypes. The reactive metabolite, 2AA, is generated by some pyridoxal 5’-phosphate (PLP)-dependent enzymes including serine/threonine dehydratase, cysteine desulfhydrase, and diaminopropionate lyase in S. enterica. In the absence of RidA, 2AA accumulates and damages other PLP-dependent enzymes, which leads to diverse phenotypes depending on the unique metabolic network of the organism.
The research that follows aimed to expand understanding RidA integration into diverse metabolic networks using Pseudomonas aeruginosa and Campylobacter jejuni as model organisms. When compared to the established paradigm from S. enterica, the data show similarities and differences in the metabolic integration of RidA in P. aeruginosa and C. jejuni. Like S. enterica, P. aeruginosa and C. jejuni encode multiple Rid enzymes, yet removing only one was sufficient to elicit metabolic defects. S. enterica, P. aeruginosa and C. jejuni ridA mutants have motility defects, suggesting the impact of 2AA accumulation is far reaching despite metabolic differences. P. aeruginosa and S. enterica share the major route of 2AA accumulation through the biosynthetic serine/threonine dehydratase, but the critically damaged enzymes differ in each organism. In C. jejuni the biosynthetic serine/threonine dehydratase was not the generator of 2AA under the conditions tested. In total, this work expanded understanding of the RidA paradigm and gave insight into the unique metabolic networks P. aeruginosa and C. jejuni.
The research that follows aimed to expand understanding RidA integration into diverse metabolic networks using Pseudomonas aeruginosa and Campylobacter jejuni as model organisms. When compared to the established paradigm from S. enterica, the data show similarities and differences in the metabolic integration of RidA in P. aeruginosa and C. jejuni. Like S. enterica, P. aeruginosa and C. jejuni encode multiple Rid enzymes, yet removing only one was sufficient to elicit metabolic defects. S. enterica, P. aeruginosa and C. jejuni ridA mutants have motility defects, suggesting the impact of 2AA accumulation is far reaching despite metabolic differences. P. aeruginosa and S. enterica share the major route of 2AA accumulation through the biosynthetic serine/threonine dehydratase, but the critically damaged enzymes differ in each organism. In C. jejuni the biosynthetic serine/threonine dehydratase was not the generator of 2AA under the conditions tested. In total, this work expanded understanding of the RidA paradigm and gave insight into the unique metabolic networks P. aeruginosa and C. jejuni.