Phenotypic characterization of overexpression or deletion of the Escherichia coli crcA, cspE and crcB genes.
The authors have previously shown that overexpression of the Escherichia coli K-12 crcA, cspE and crcB genes protects the chromosome from decondensation by camphor. In this study they examine the phenotypic consequences of deleting or overexpressing crcA, cspE and crcB. Overexpressing crcA, cspE and crcB increases supercoiling levels of plasmids in wild-type cells and in temperature-sensitive (Ts) gyrase mutants, suppresses the sensitivity of gyrase and topoisomerase IV (topo IV) Ts mutants to nalidixic acid, makes gyrase and topo IV Ts mutants more resistant to camphor and corrects the nucleoid morphology defects in topo IV Ts mutants. Overexpression of crcA, cspE and crcB results in a slight (2.2-fold) activation of the rcsA gene. Deleting crcA, cspE and crcB is not lethal to cells but results in an increase in sensitivity to camphor. Deletion of crcA, cspE and crcB exacerbates the nucleoid morphology defects of the topo IV Ts mutants. When the individual crcA, cspE or crcB genes were tested for their effects on camphor resistance and regulation of rcsA, cspE alone conferred 10-fold camphor resistance and 1.7-fold activation of rcsA. These activities were augmented when crcB was overexpressed with cspE (100-fold camphor resistance and 2.1-fold induction of rcsA).
Sand
Olivier
O
Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4255, USA.
Gingras
Monica
M
Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4255, USA.
Beck
Nancy
N
Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4255, USA.
Hall
Christine
C
Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4255, USA.
Trun
Nancy
N
Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA.|Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4255, USA.
D001483:Base Sequence; D002164:Camphor / Q000494:pharmacology; D003001:Cloning, Molecular; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D029968:Escherichia coli Proteins / Q000235:genetics; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics; D009154:Mutation; D009268:Nalidixic Acid / Q000494:pharmacology; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D013696:Temperature; D014466:Ultraviolet Rays
C088097:CspE protein, E coli; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D009268:Nalidixic Acid; D002164:Camphor; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase