title: Respiration and the F₁Fo-ATPase enhance survival under acidic conditions in Escherichia coli.
abstract: Besides amino acid decarboxylation, the ADP biosynthetic pathway was reported to enhance survival under extremely acidic conditions in Escherichia coli (Sun et al., J. Bacteriol. 193∶ 3072-3077, 2011). E. coli has two pathways for ATP synthesis from ADP: glycolysis and oxidative phosphorylation. We found in this study that the deletion of the F(1)Fo-ATPase, which catalyzes the synthesis of ATP from ADP and inorganic phosphate using the electro-chemical gradient of protons generated by respiration in E. coli, decreased the survival at pH 2.5. A mutant deficient in hemA encoding the glutamyl tRNA reductase, which synthesizes glutamate 1-semialdehyde also showed the decreased survival of E. coli at pH 2.5. Glutamate 1-semialdehyde is a precursor of heme synthesis that is an essential component of the respiratory chain. The ATP content decreased rapidly at pH 2.5 in these mutants as compared with that of their parent strain. The internal pH was lowered by the deletion of these genes at pH 2.5. These results suggest that respiration and the F(1)Fo-ATPase are still working at pH 2.5 to enhance the survival under such extremely acidic conditions.
authors.affiliation: Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong, People's Republic of China. sunyr1206@163.com
authors.forename: Yirong
authors.initials: Y
authors.lastname: Sun
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Fukamachi
authors.forename: Hiromi
authors.initials: H
authors.lastname: Saito
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kobayashi
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D006418:Heme / Q000096:biosynthesis; D006863:Hydrogen-Ion Concentration; D042541:Intracellular Space / Q000737:chemistry; D050296:Microbial Viability; D009154:Mutation; D010085:Oxidative Phosphorylation; D006180:Proton-Translocating ATPases / Q000378:metabolism*
chemical_list: D006418:Heme; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases