title: Partial suppression of the phenotype of Escherichia coli K-12 dnaG mutants by some I-like conjugative plasmids.
abstract: Three I-like conjugative plasmids, ColIdrd1, R144drd3, and R64drd11, which are derepressed for functions involved in conjugation, were found to suppress at least partially the phenotype of temperature-sensitive dnaG mutants of Escherichia coli K-12, as judged from the kinetics of deoxyribonucleic acid synthesis at elevated temperature in newly formed and established plasmid-containing strains. In contrast, the corresponding wild-type plasmids and three F-like derepressed conjugative plasmids, F101, R100drd1, and R1drd16, all failed to suppress. Suppression is presumably caused by a different plasmid-determined function from that which promotes survival of ultraviolet-irradiated bacteria, because both the wild-type I-like plasmids and their drd mutants protected irradiated bacteria. One possible interpretation of these results is that the product of a gene carried by certain I-like plasmids can substitute for the bacterial dnaG gene product during ongoing deoxyribonucleic acid replication.
mesh_terms: D002250:Carbon Radioisotopes; D003087:Colicins / Q000494:pharmacology*; D003227:Conjugation, Genetic; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects; D005111:Extrachromosomal Inheritance; D009154:Mutation; D010641:Phenotype; D011830:Radiation Effects; D013489:Suppression, Genetic; D013696:Temperature; D013941:Thymine / Q000378:metabolism; D014316:Tritium; D014466:Ultraviolet Rays
chemical_list: D002250:Carbon Radioisotopes; D003087:Colicins; D004269:DNA, Bacterial; D014316:Tritium; D013941:Thymine