Involvement of DnaK protein in mini-F plasmid replication: Temperature-sensitive seg mutations are located in the dnaK gene

Bunichi Ezaki, Teru Ogura, Hirotada Mori, Hironori Niki, Sota Hiraga

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

The seg mutants (seg-1 and seg-2) of Escherichia coli cannot support the replication of the F factor and mini-F plasmids at 42°C. We cloned the wild-type E. coli chromosomal DNA fragment complementing the seg-1 and seg-2 mutations and found that both mutations were complemented by the wild-type dnaK gene coding for a heat shock protein. Transduction with phage P1 indicated that the seg-2 mutation is located at about 0.3 min in the region containing the dnaK gene in the order trpR-thrA-seg-2-leuB, consistent with the locus of the dnaK gene. Cloning and sequencing of the dnaK gene of the seg mutants showed that there was one base substitution within the dnaK gene in each mutant causing an amino acid substitution. These results indicate that the seg gene in which the seg-1 and seg-2 mutations occurred is identical to the dnaK gene. The mini-F plasmid pXX325 did not transform a dnaK null mutant to ampicillin resistance at 30°C in contrast to plasmids pBR322, pACYC184 and pSC101, which did. The active dnaK (seg) gene product is therefore essential for replication of the mini-F plasmid at both 30° and 42°C.

Original languageEnglish
Pages (from-to)183-189
Number of pages7
JournalMGG Molecular & General Genetics
Volume218
Issue number2
DOIs
Publication statusPublished - Aug 1989
Externally publishedYes

Fingerprint

F Factor
Mutation
Temperature
Genes
Proteins
Bacteriophage P1
Escherichia coli
Ampicillin Resistance
Gene Order
Amino Acid Substitution
Heat-Shock Proteins
Organism Cloning
Plasmids
DNA

Keywords

  • dnaK gene
  • F plasmid
  • Replication
  • seg mutations

ASJC Scopus subject areas

  • Genetics

Cite this

Involvement of DnaK protein in mini-F plasmid replication : Temperature-sensitive seg mutations are located in the dnaK gene. / Ezaki, Bunichi; Ogura, Teru; Mori, Hirotada; Niki, Hironori; Hiraga, Sota.

In: MGG Molecular & General Genetics, Vol. 218, No. 2, 08.1989, p. 183-189.

Research output: Contribution to journalArticle

Ezaki, Bunichi ; Ogura, Teru ; Mori, Hirotada ; Niki, Hironori ; Hiraga, Sota. / Involvement of DnaK protein in mini-F plasmid replication : Temperature-sensitive seg mutations are located in the dnaK gene. In: MGG Molecular & General Genetics. 1989 ; Vol. 218, No. 2. pp. 183-189.
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