Defective initiation in an Escherichia coli dnaA(Cs,Sx) mutant

Mutations in the Escherichia coli gene for initiation of DNA replication, d naA, which suppress the polymerization defect and growth inhibition caused by temperature-sensitive (Ts) mutations in the polymerization gene, dnaX, a re called Cs,Sx. We show here that these mutations, on their own, also caus e defects in initiation, including inhibition of initiation at both low (20 degreesC) and high (44 degreesC) temperatures and asynchronous initiation at both the permissive (34 degreesC) and suppression (39 degreesC) temperat ures. These findings suggests a relationship between partially defective in itiation and suppression of the polymerization defect. both of which occur at 39 degreesC. (C) 2001 Societe francaise de biochimie et biologie molecul aire / Editions scientifiques et medicales Elsevier SAS.