title: Requirement of purine and pyrimidine synthesis for colonization of the mouse intestine by Escherichia coli.
abstract: To study the adaptation of an intestinal bacterium to its natural environment, germfree mice were associated with commensal Escherichia coli MG1655. Two-dimensional gel electrophoresis was used to identify proteins differentially expressed in E. coli MG1655 collected from either cecal contents or anaerobic in vitro cultures. Fourteen differentially expressed proteins (>3-fold; P < 0.05) were identified, nine of which were upregulated in cecal versus in vitro-grown E. coli. Four of these proteins were investigated further for their role in gut colonization. After deletion of the corresponding genes, the resulting E. coli mutants were tested for their ability to colonize the intestines of gnotobiotic mice in competition with the wild-type strain. A mutant devoid of ydjG, which encodes a putative NADH-dependent methylglyoxal reductase, reached a 1.2-log-lower cecal concentration than the wild type. Deletion of the nanA gene encoding N-acetylneuraminate lyase affected the colonization and persistence of E. coli in the intestines of the gnotobiotic mice only slightly. A mutant devoid of 5'-phosphoribosyl 4-(N-succinocarboxamide)-5-aminoimidazole synthase, a key enzyme of purine synthesis, displayed intestinal cell counts >4 logs lower than those of the wild type. Deletion of the gene encoding aspartate carbamoyltransferase, a key enzyme of pyrimidine synthesis, even resulted in the washout of the corresponding mutant from the mouse intestinal tract. These findings indicate that E. coli needs to synthesize purines and pyrimidines to successfully colonize the mouse intestine.
authors.affiliation: Department of Gastrointestinal Microbiology, German Institute of Human Nutrition, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Vogel-Scheel
authors.forename: Carl
authors.initials: C
authors.lastname: Alpert
authors.forename: Wolfram
authors.initials: W
authors.lastname: Engst
authors.forename: Gunnar
authors.initials: G
authors.lastname: Loh
authors.forename: Michael
authors.initials: M
authors.lastname: Blaut
mesh_terms: D000429:Alcohol Oxidoreductases / Q000172:deficiency; D000818:Animals; D001221:Aspartate Carbamoyltransferase / Q000172:deficiency; D019731:Carbon-Nitrogen Ligases / Q000172:deficiency; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000254:growth & development / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics; D041981:Gastrointestinal Tract / Q000382:microbiology*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D005856:Germ-Free Life; D051379:Mice; D007652:Oxo-Acid-Lyases / Q000172:deficiency; D011687:Purines / Q000096:biosynthesis*; D011743:Pyrimidines / Q000096:biosynthesis*; D014774:Virulence
chemical_list: D029968:Escherichia coli Proteins; D011687:Purines; D011743:Pyrimidines; D000429:Alcohol Oxidoreductases; C031416:D-lactaldehyde dehydrogenase; D001221:Aspartate Carbamoyltransferase; D007652:Oxo-Acid-Lyases; C018728:N-acetylneuraminate lyase; D019731:Carbon-Nitrogen Ligases; C022380:phosphoribosylaminoimidazole synthase; C030986:pyrimidine; C030985:purine