CONTROL OF THE INITIATION OF DNA-REPLICATION IN ESCHERICHIA-COLI .2. FUNCTION OF THE DNAA PRODUCT

General growth parameters and the kinetics of DNA replication have been determined in merogenotes carrying different combinations of the dnaA+ and the dnaA5 allele. The strain which is homozygous diploid for dnaA5 is different from all other combinations in cell volume, DNA per mass ratio, number of replication points per chromosome, and polymerization rate of DNA. From this we deduce that the dnaA product is a positively acting regulatory protein in initiation. In an appendix we show that in combinations between the dnaA5 and dnaA204 alleles the phenotype of dnaA5 is dominant. © 1979 Springer-Verlag.