Novel alleles of the Escherichia coli dnaA gene are defective in replication of pSC101 but not of oriC.
Five novel alleles of the Escherichia coli dnaA gene that were temperature sensitive in maintenance of pSC101, a plasmid that is dependent on this gene for replication, were isolated. Nucleotide sequence analysis revealed that four of the five alleles arose from single base substitutions, whereas the fifth contained three base substitutions, two of which were silent. Whereas all five alleles were temperature sensitive in vivo for pSC101 maintenance, genetic and biochemical characterization indicated that only two were defective in replication from the chromosomal origin, oriC. As previously characterized mutations are defective in replication for both pSC101 and oriC, the dnaA mutations specifically defective in pSC101 maintenance represent a novel class. We speculate that one or more of these pSC101-specific mutants are defective in interaction with pSC101 RepA protein, which is also required for initiation of plasmid DNA replication.
Sutton
M D
MD
Department of Biochemistry, Michigan State University, East Lansing 48824-1319, USA.
Kaguni
J M
JM
D000483:Alleles; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D004265:DNA Helicases; D004261:DNA Replication / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D017354:Point Mutation; D011506:Proteins; D018741:Replication Origin / Q000235:genetics; D017422:Sequence Analysis, DNA; D013696:Temperature; D015534:Trans-Activators
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; D011506:Proteins; D015534:Trans-Activators; C045264:replication initiator protein; D004265:DNA Helicases