title: Viability of folA-null derivatives of wild-type (thyA+) Escherichia coli K-12.
abstract: Dihydrofolate reductase (the folA gene product) catalyzes the synthesis of tetrahydrofolate, a key methyl donor in many biosynthetic pathways. Loss of folA had been thought to be lethal to wild-type (thyA+) Escherichia coli. Viable folA-null derivatives of thyA+ E. coli were obtained, however, by recombining a folA deletion linked to a Kanr selectable marker into a lambda folA+ phage and using this phage to transduce cells to kanamycin resistance. folA-null strains were slow growing, formed small colonies, and were auxotrophic for thymidine, adenine, methionine, glycine, and pantothenate.
authors.affiliation: Department of Molecular Microbiology, Washington University Medical School, St. Louis, Missouri 63110.
authors.forename: B R
authors.initials: BR
authors.lastname: Krishnan
authors.forename: D E
authors.initials: DE
authors.lastname: Berg
mesh_terms: D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D017353:Gene Deletion; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D009838:Oligodeoxyribonucleotides; D013762:Tetrahydrofolate Dehydrogenase