Missense mutations in the 3' end of the Escherichia coli dnaG gene do not abolish primage activity but do confer the chromosome-segregation-defective (par) phenotype

James Versalovic, James R. Lupski

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Isogenic dnaG strains of Escherichia coli with the parB and dnaG2903 alleles in the MG1655 chromosomal background displayed the classic par phenotype at the nonpermissive temperature of 42°C. These strains synthesized DNA at 42°C, but remained chromosome segregation defective as determined by cytology. A strain with the dnaG2903 allele was tested for its ability to support DNA replication of a primase-dependent G4ori(c)-containing M13 phage derivative by quantitative competitive PCR (QC-PCR). The dnaG2903 strain converted the single-stranded DNA into double-stranded replicative form DNA at 42°C. These results indicate that DnaG2903 retains primase activity at the restrictive temperature. Nucleoids remained unsegregated in the central region of cell filaments at 42°C. The observed suppression of cell filamentation in dnaG sfiA or dnaG lexA double mutants suggests that the SOS response is induced at the restrictive temperature in parB and dnaG2903 strains but fails to account entirely for the cell filamentation phenotype. ParB and DnaG2903 presumably can synthesize primer RNA for DNA replication, but may be defective in their interactions with DNA replication proteins, cell cycle regulatory factors, or the chromosome segregation apparatus itself.

Original languageEnglish (US)
Pages (from-to)585-594
Number of pages10
JournalMicrobiology
Volume143
Issue number2
DOIs
StatePublished - Jan 1 1997

Keywords

  • Chromosome
  • DNA replication
  • Partitioning
  • Segregation
  • SOS response

ASJC Scopus subject areas

  • Microbiology

Fingerprint Dive into the research topics of 'Missense mutations in the 3' end of the Escherichia coli dnaG gene do not abolish primage activity but do confer the chromosome-segregation-defective (par) phenotype'. Together they form a unique fingerprint.

Cite this