title: beta-Alanine auxotrophy associated with dfp, a locus affecting DNA synthesis in Escherichia coli.
abstract: Strains containing the conditional-lethal dfp-707 mutation, which have a defect in DNA synthesis at 42 degrees C, were found to require either pantothenate or its precursor, beta-alanine, for growth at 30 degrees C. The auxotrophy and conditional lethality were corevertible. Through localized mutagenesis of the dfp-pyrE region of Escherichia coli, another mutation, dfp-1, was obtained. It conferred the auxotrophy but not the conditional lethality of dfp-707. Complementation analysis, performed with a set of plasmid-borne deletion and insertion mutations, revealed a correspondence between the complementation of each mutant phenotype and the production of the dfp gene product, previously identified as a 45-kilodalton flavoprotein. The dfp mutants had a normal level of aspartate-1-decarboxylase, which is the only enzyme known to produce beta-alanine in E. coli and which is specified by the distant panD gene. A prototrophic pseudorevertant of a dfp-1 strain was found to have retained the dfp mutation, to be genetically unstable, and to have an elevated level of aspartate-1-decarboxylase, suggesting that it had acquired a duplication of panD. It is not known what steps in pantothenate or DNA metabolism are affected by the mutant dfp product or how its flavin moiety may be involved.
mesh_terms: D000409:Alanine / Q000378:metabolism*; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D005968:Glutamate Decarboxylase / Q000235:genetics; D009154:Mutation; D010205:Pantothenic Acid / Q000235:genetics / Q000378:metabolism; D010957:Plasmids; D013696:Temperature; D015091:beta-Alanine / Q000235:genetics / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D015091:beta-Alanine; D010205:Pantothenic Acid; C019104:aspartate-alpha-decarboxylase; D005968:Glutamate Decarboxylase; D000409:Alanine