Induction of a mutant DnaA protein (DnaA E204Q) with decreased intrinsic ATPase activity in cells was previously shown to cause overinitiation of chromosomal DNA replication and a dominant lethal phenotype. Here it is shown that the dominant lethality required incubation at high temperatures; cells harboring the expression plasmid of DnaA E204Q showed very weak colony formation ability (less than 1/105 that of the wild-type DnaA) at 42°C, whereas they showed a normal colony formation ability at 28°C on LB agar plates. Overinitiation of chromosomal DNA replication caused by expression of DnaA E204Q also required incubation at high temperatures in LB medium. When the incubation was performed in synthetic (Tanaka) medium at 42°C, neither the dominant lethality nor overinitiation caused by expressing DnaA E204Q was observed. These results suggest that the dominant lethality and the overinitiation caused by expressing DnaA E204Q require culture conditions that provide a high potential for cell growth.
ASJC Scopus subject areas
- Molecular Biology