RRC ID 4926
Author Fujimitsu K, Su'etsugu M, Yamaguchi Y, Mazda K, Fu N, Kawakami H, Katayama T.
Title Modes of overinitiation, dnaA gene expression, and inhibition of cell division in a novel cold-sensitive hda mutant of Escherichia coli.
Journal J Bacteriol
Abstract The chromosomal replication cycle is strictly coordinated with cell cycle progression in Escherichia coli. ATP-DnaA initiates replication, leading to loading of the DNA polymerase III holoenzyme. The DNA-loaded form of the beta clamp subunit of the polymerase binds the Hda protein, which promotes ATP-DnaA hydrolysis, yielding inactive ADP-DnaA. This regulation is required to repress overinitiation. In this study, we have isolated a novel cold-sensitive hda mutant, the hda-185 mutant. The hda-185 mutant caused overinitiation of chromosomal replication at 25 degrees C, which most likely led to blockage of replication fork progress. Consistently, the inhibition of colony formation at 25 degrees C was suppressed by disruption of the diaA gene, an initiation stimulator. Disruption of the seqA gene, an initiation inhibitor, showed synthetic lethality with hda-185 even at 42 degrees C. The cellular ATP-DnaA level was increased in an hda-185-dependent manner. The cellular concentrations of DnaA protein and dnaA mRNA were comparable at 25 degrees C to those in a wild-type hda strain. We also found that multiple copies of the ribonucleotide reductase genes (nrdAB or nrdEF) or dnaB gene repressed overinitiation. The cellular levels of dATP and dCTP were elevated in cells bearing multiple copies of nrdAB. The catalytic site within NrdA was required for multicopy suppression, suggesting the importance of an active form of NrdA or elevated levels of deoxyribonucleotides in inhibition of overinitiation in the hda-185 cells. Cell division in the hda-185 mutant was inhibited at 25 degrees C in a LexA regulon-independent manner, suggesting that overinitiation in the hda-185 mutant induced a unique division inhibition pathway.
Volume 190(15)
Pages 5368-81
Published 2008-8-1
DOI 10.1128/JB.00044-08
PII JB.00044-08
PMID 18502852
PMC PMC2493284
MeSH Adenosine Triphosphatases / genetics Adenosine Triphosphatases / metabolism* Bacterial Outer Membrane Proteins / genetics Bacterial Proteins / genetics Bacterial Proteins / metabolism* Carrier Proteins / genetics Cell Division* Cold Temperature Cytosol / chemistry DNA Replication* DNA-Binding Proteins / genetics DNA-Binding Proteins / metabolism* Deoxyadenine Nucleotides / analysis Deoxycytosine Nucleotides / analysis DnaB Helicases / genetics Escherichia coli / cytology* Escherichia coli / genetics Escherichia coli / growth & development Escherichia coli Proteins / genetics Escherichia coli Proteins / metabolism* Gene Dosage Gene Expression Profiling Hot Temperature Mutagenesis, Insertional Mutation Ribonucleoside Diphosphate Reductase / genetics Ribonucleotide Reductases / genetics
IF 3.234
Times Cited 45
Prokaryotes E. coli ME9018 JW3118