IDENTIFICATION OF DNAX AS A HIGH-COPY SUPPRESSOR OF THE CONDITIONAL-LETHAL AND PARTITION PHENOTYPES OF THE PARE10 ALLELE

Termination of DNA replication, complete topological unlinking of the parental template DNA strands, partition of the daughter chromosomes, and cell division follow in an ordered and interdependent sequence dur ing normal bacterial growth, In Escherichia coli, topoisomerase IV (To po IV), encoded by parE and parC, is responsible for decatenation of t he two newly formed chromosomes, In an effort to uncover the pathway o f information flow between the macromolecular processes that describe these events, we identified dnaX, encoding the tau and gamma subunits of the DNA polymerase III holoenzyme, as a high-copy suppressor of the temperature-sensitive phenotype of the parE10 allele, We show that su ppression derives from overexpression of the gamma, but not the tau, s ubunit of the holoenzyme and that the partition defect of parE10 cells is nearly completely reverted at the nonpermissive temperature as wel l, These observations suggest a possible association between Topo IV a nd the replication machinery.