Related Experiment Videos
De novo pyrimidine synthesis is necessary for intestinal colonization of Salmonella Typhimurium in chicks
Hee-Jeong Yang1, Lydia Bogomolnaya1,2, Michael McClelland3
1Department of Microbial and Molecular Pathogenesis, College of Medicine, Texas A&M University System Health Science Center, Bryan, TX, United States of America.
Insights
Salmonella Typhimurium requires de novo pyrimidine synthesis for chick colonization. The pyrimidine salvage pathway is not utilized in the chick intestine, impacting bacterial growth.
Area of Science:
- Microbiology
- Pathogenesis
- Biochemistry
Background:
- The de novo pyrimidine biosynthetic pathway is essential for microbial survival.
- The pyrE gene encodes orotate phosphoribosyltransferase (OPRTase), a key enzyme in this pathway.
- Salmonella Typhimurium is a significant pathogen affecting various hosts.
Purpose of the Study:
- To investigate the role of pyrE in Salmonella Typhimurium colonization in chicks.
- To determine the contribution of de novo pyrimidine synthesis versus salvage pathways during infection.
- To identify host-specific factors influencing Salmonella growth.
Main Methods:
- Construction and characterization of a ΔpyrE mutant.
- Competitive infection assays in 4-day-old chicks.
- In vitro growth assays under nutrient-limited conditions.
- Complementation studies and supplementation with pyrimidine precursors.
Main Results:
- A ΔpyrE mutant exhibited significantly reduced colonization in chicks compared to wild-type Salmonella.
- The colonization defect was restored by providing pyrE in trans.
- The mutant displayed poor growth in nutrient-poor conditions, which was rescued by pyrimidine salvage pathway precursors.
- Colonization defects were specific to chicks, not observed in mice or calves.
Conclusions:
- De novo pyrimidine synthesis is critical for Salmonella Typhimurium colonization in the chick intestinal environment.
- The chick intestine environment during infection is insufficient in pyrimidine salvage precursors for Salmonella growth.
- The pyrimidine salvage pathway is not utilized by Salmonella Typhimurium in the chick niche, highlighting host-pathogen metabolic interactions.
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.