De novo pyrimidine synthesis is necessary for intestinal colonization of Salmonella Typhimurium in chicks

Abstract

pyrE (STM3733) encodes orotate phosphoribosyltransferase (OPRTase; EC 2.4.2.10), the fifth enzyme of the de novo pyrimidine biosynthetic pathway. We identified a ΔpyrE mutant as under selection in screening of a Salmonella mutant library in 4-day old chicks. Here, we confirm that a ΔpyrE mutant colonizes 4-day old chicks poorly in competitive infection with isogenic wild type, and that the ability of this mutant to colonize chicks could be restored by providing a copy of pyrE in trans. We further show that our ΔpyrE mutant grows poorly in nutrient poor conditions in vitro, and that the ability of this mutant to grow is restored, both in vitro and in chicks, when precursors to the pyrimidine salvage pathway were provided. This finding suggests that the environment in the chick intestine during our infections lacks sufficient precursors of the pyrimidine salvage pathway to support Salmonella growth. Finally, we show that the colonization defect of a ΔpyrE mutant during infection occurs in to chicks, but not in CBA/J mice or ligated ileal loops in calves. Our data suggest that de novo pyrimidine synthesis is necessary for colonization of Salmonella Typhimurium in the chick, and that the salvage pathway is not used in this niche.

Sequential evolution of virulence and resistance during clonal spread of community-acquired methicillin-resistant Staphylococcus aureus

“…2F). Collectively, the data provide experimental evidence for the S. aureus pyr operon being a colonization determinant, as previously seen with Escherichia coli and Salmonella (43,44). The data also (i) indicate that pyrR mutation confers an advantage to the bacterium during competition with other strains both in culture and in the mammalian intestine, and (ii) suggest that mutation of pyrR enhances commensal rather than pathogenic fitness.…”

Non-Caloric Artificial Sweeteners Modulate the Expression of Key Metabolic Genes in the Omnipresent Gut Microbe <b><i>Escherichia coli</i></b>

“…These encode important rate-limiting enzymes of glucose catabolism. De novo pyrimidine synthesis was shown to be necessary for the colonization of Salmonella typhimurium in chicks [Yang et al, 2017]. Genes of two important enzymes in the de novo synthesis of pyrimidine (ThyA and Tmk) in E. coli showed a relatively higher expression with increased concentrations of NAS.…”

Identification of genes required for the fitness of <i>Rhodococcus equi</i> during the infection of mice via signature-tagged transposon mutagenesis

“…A pyrE gene encoding an orotate phosphoribosyltransferase was identified as in vivo fitness gene of R. equi; PyrE is an enzyme that works in the fifth stage of the pyrimidine biosynthesis pathway and catalyzes the production of orotidine 5ʹ′ -monophosphate from orotic acid and phosphoribosyl pyrophosphate [5]. The deletion of pyrE results in pyrimidine auxotroph in Listeria monocytogenes and Salmonella Typhimurium [16,58]. The transcription of pyrE in L. monocytogenes has been reported to increase at the onset of macrophage infection, suggesting a low pyrimidine concentration in the phagosome.…”