Stability and replication control of Escherichia coli minichromosomes.

摘要: A stabilized minichromosome--a plasmid replicating from the chromosomal origin oriC--was constructed by cloning sopA,B,C, genes F. This minichromosome had a loss frequency of less than 10(-3), while that nonstabilized parental was 2 X 10(-2) to 4 10(-2). Both minichromosomes same average copy number per origin, and numbers were constant over an eightfold range growth rates. Different mutations in mioC gene promoter, which transcription enters oriC, constructed, their effects on stability tested. The results indicated normal replication control at oriC independent MioC protein most sequences between promoter but required both probably also presence DnaA box (DnaA protein-binding site) just upstream promoter. Transcription shown be efficiently repressed vivo after overproduction derepressed nonpermissive temperature six different dnaA(Ts) mutants.