title: Exposure of Escherichia coli to acid habituation conditions sensitizes it to alkaline stress.
abstract: Escherichia coli transferred from pHo 7.0 to pHo 5.5 or 6.0 became alkali-sensitive by a rapidly induced phenotypic response. Alkali sensitization was reduced at pHo 5.0 and virtually abolished at pHo 6.5. The response was triggered by cytoplasmic rather than external or periplasmic acidification and de novo protein synthesis was needed. Alkali sensitivity failed to appear at pHo 5.5 plus DNA gyrase inhibitors and was markedly reduced by himA, himD, hns, ompC and nhaA lesions. A tonB deletion mutant showed alkali sensitivity at pHo 7.0. Alkali sensitivity induction was not subject to catabolite repression nor was it appreciably affected by a relA lesion. Acid-induced cells were more sensitive to alkali damage to both DNA and beta-galactosidase and to alkali inhibition of beta-galactosidase induction. Alkali sensitization induced at pHo 5.5 may involve NhaB loss.
authors.affiliation: Department of Biology (Darwin), University College London, UK.
authors.forename: R J
authors.initials: RJ
authors.lastname: Rowbury
authors.forename: N H
authors.initials: NH
authors.lastname: Hussain
mesh_terms: D000468:Alkalies / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003470:Culture Media; D004269:DNA, Bacterial / Q000187:drug effects / Q000378:metabolism; D004790:Enzyme Induction; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D010641:Phenotype; D001616:beta-Galactosidase / Q000096:biosynthesis
chemical_list: D000468:Alkalies; D001426:Bacterial Proteins; D003470:Culture Media; D004269:DNA, Bacterial; D001616:beta-Galactosidase