title: Deletion ofnudBCauses Increased Susceptibility to Antifolates in Escherichia coli and Salmonella enterica.
abstract: Co-trimoxazole, a fixed-dose combination of sulfamethoxazole (SMX) and trimethoprim (TMP), has been used for the treatment of bacterial infections since the 1960s. Since it has long been assumed that the synergistic effects between SMX and TMP are the consequence of targeting 2 different enzymes of bacterial folate biosynthesis, 2 genes (pabBandnudB) involved in the folate biosynthesis ofEscherichia coliwere deleted, and their effects on the susceptibility to antifolates were tested. The results showed that the deletion ofnudBresulted in a lag of growth in minimal medium and increased susceptibility to both SMX and TMP. Moreover, deletion ofnudBalso greatly enhanced the bactericidal effect of TMP. To elucidate the mechanism of how the deletion ofnudBaffects the bacterial growth and susceptibility to antifolates, 7,8-dihydroneopterin and 7,8-dihydropteroate were supplemented into the growth medium. Although those metabolites could restore bacterial growth, they had no effect on susceptibilities to the antifolates. Reverse mutants of thenudBdeletion strain were isolated to further study the mechanism of how the deletion ofnudBaffects susceptibility to antifolates. Targeted sequencing and subsequent genetic studies revealed that the disruption of the tetrahydromonapterin biosynthesis pathway could reverse the phenotype caused by thenudBdeletion. Meanwhile, overexpression offolMcould also lead to increased susceptibility to both SMX and TMP. These data suggested that the deletion ofnudBresulted in the excess production of tetrahydromonapterin, which then caused the increased susceptibility to antifolates. In addition, we found that the deletion ofnudBalso resulted in increased susceptibility to both SMX and TMP inSalmonella entericaSince dihydroneopterin triphosphate hydrolase is an important component of bacterial folate biosynthesis and the tetrahydromonapterin biosynthesis pathway also exists in a variety of bacteria, it will be interesting to design new compounds targeting dihydroneopterin triphosphate hydrolase, which may inhibit bacterial growth and simultaneously potentiate the antimicrobial activities of antifolates targeting other components of folate biosynthesis.
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Li
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Li
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Yang
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
authors.forename: Xu-De
authors.initials: XD
authors.lastname: Wang
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
authors.forename: Lei-Xin
authors.initials: LX
authors.lastname: Gao
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
authors.forename: Rui-Qi
authors.initials: RQ
authors.lastname: Wang
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Gu
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China x.zhang@wh.iov.cn dengjy@wh.iov.cn.
authors.forename: Xian-En
authors.initials: XE
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China x.zhang@wh.iov.cn dengjy@wh.iov.cn.
authors.forename: Jiao-Yu
authors.initials: JY
authors.lastname: Deng
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D005493:Folic Acid Antagonists / Q000494:pharmacology*; D017353:Gene Deletion; D008826:Microbial Sensitivity Tests; D019798:Neopterin / Q000031:analogs & derivatives / Q000494:pharmacology; D011622:Pterins / Q000494:pharmacology; D011755:Pyrophosphatases / Q000037:antagonists & inhibitors / Q000235:genetics*; D019779:Salmonella enterica / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D005493:Folic Acid Antagonists; D011622:Pterins; C000976:7,8-dihydroneopterin; C000978:dihydropteroate; D019798:Neopterin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; C479919:FolM protein, E coli; D013762:Tetrahydrofolate Dehydrogenase; C546903:NudB protein, E coli; D011755:Pyrophosphatases; C023129:dihydroneopterin triphosphate pyrophosphohydrolase
keywords: nudB; sulfamethoxazole; susceptibility; tetrahydromonapterin; trimethoprim