title: Different effects of ppGpp on Escherichia coli DNA replication in vivo and in vitro.
abstract: Inhibition of Escherichia coli DNA replication by guanosine tetraphosphate (ppGpp) is demonstrated in vitro. This finding is compatible with impairment of the DnaG primase activity by this nucleotide. However, in agreement to previous reports, we were not able to detect a rapid inhibition of DNA synthesis in E. coli cells under the stringent control conditions, when intracellular ppGpp levels increase dramatically. We suggest that the process of ppGpp-mediated inhibition of DnaG activity may be masked in E. coli cells, which could provide a rationale for explanation of differences between ppGpp effects on DNA replication in E. coli and Bacillus subtilis.
authors.affiliation: Department of Molecular Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Maciąg-Dorszyńska
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Szalewska-Pałasz
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Węgrzyn
keywords: DNA replication; Guanosine tetraphosphate (ppGpp); In vitro DNA synthesis; Stringent response; ppGpp, guanosine tetraphosphate; pppGpp, guanosine pentaphosphate.