title: Mutants of Escherichia coli B-r defective in deoxyribonucleic acid initiation: dnaI, a new gene for replication.
abstract: Mutagenized E. coli B/r cells were subjected to a procedure designed to select mutants temperature-sensitive for initiation of deoxyribonucleic acid (DNA) replication. Seventeen mutants exhibiting limited residual DNA synthesis at 42 C were obtained and the dna(-) sites were mapped genetically. Sixteen of the sites map near dnaA, dnaB, and dnaC. One mutant (dna-208) maps in a new location between the trp and his genes. We propose to call this mutant dnaI208. In complementation experiments dnaC(+) and dnaI(+) were dominant to dnaC(-) and dnaI(-) alleles, respectively. However, dnaA(-) was dominant to the wild-type allele dnaA(+). All dnaA mutants and four out of six dnaC mutants could be suppressed by F factor integration. The pattern of suppression was specific for each mutant.
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis; D002250:Carbon Radioisotopes; D002452:Cell Count; D002874:Chromosome Mapping; D003227:Conjugation, Genetic; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis*; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D005796:Genes; D005816:Genetic Complementation Test; D007930:Leucine / Q000378:metabolism; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D013489:Suppression, Genetic; D013696:Temperature; D013941:Thymine / Q000378:metabolism; D014161:Transduction, Genetic; D014316:Tritium
chemical_list: D001426:Bacterial Proteins; D002250:Carbon Radioisotopes; D004269:DNA, Bacterial; D009153:Mutagens; D009604:Nitrosoguanidines; D014316:Tritium; D007930:Leucine; D013941:Thymine