Department of Microbial and Molecular Pathogenesis, College of Medicine, Texas A&M University System Health Science Center, Bryan, TX, United States of America.
Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia.
PLoS One. 2017 Oct 17;12(10):e0183751. doi: 10.1371/journal.pone.0183751. eCollection 2017.
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.
pyrE (STM3733) 编码乳清酸磷酸核糖基转移酶 (OPRTase; EC 2.4.2.10)，这是从头合成嘧啶生物合成途径的第五种酶。我们在对 4 日龄雏鸡的沙门氏菌突变体文库进行筛选时发现了一个 ΔpyrE 突变体被选择。在这里，我们证实与同基因野生型相比，ΔpyrE 突变体在竞争性感染 4 日龄雏鸡时定植能力较差，并且该突变体在雏鸡中定植的能力可以通过提供 pyrE 的拷贝来恢复。我们进一步表明，我们的 ΔpyrE 突变体在体外营养条件差的情况下生长不良，并且当提供嘧啶补救途径的前体时，该突变体在体外和雏鸡中恢复生长的能力。这一发现表明，在我们的感染过程中，鸡肠内的环境缺乏足够的嘧啶补救途径前体来支持沙门氏菌的生长。最后，我们表明在感染过程中 ΔpyrE 突变体的定植缺陷发生在雏鸡中，但不在 CBA/J 小鼠或小牛结扎回肠环中。我们的数据表明，从头合成嘧啶对于沙门氏菌 Typhimurium 在鸡中的定植是必要的，并且在这个生态位中不使用补救途径。
