title: Suppression of an Escherichia coli dnaA mutation by the integrated R factor R100.1: origin of chromosome replication during exponential growth.
abstract: We have investigated the behavior, during exponential growth, of strains of Escherichia coli carrying a dnaA(Ts) mutation that has been suppressed by the integration of the F-like R plasmid R100.1. We present evidence showing that replication in these strains proceeds largely from the normal chromosome origin at 30 degrees C, a permissive temperature for the dnaA(Ts) gene product, whereas, at 42 degrees C, replication proceeds largely from the integrated plasmid. These conclusions are based on measurements made by deoxyribonucleic acid:deoxyribonucleic acid hybridization of the relative frequencies of the prophages Mu-1 and lambdaind- and R100.1 integrated at known locations on the E. coli chromosome in these Hfr strains.
mesh_terms: D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial / Q000378:metabolism*; D003090:Coliphages; D004261:DNA Replication; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D005796:Genes; D009154:Mutation; D011815:R Factors; D013696:Temperature