Dominant lethal mutations in the dnaB helicase gene of Salmonella typhimurium.
AUTOR(ES)
Maurer, R
RESUMO
A class of dominant lethal mutations in the dnaB (replicative helicase) gene of Salmonella typhimurium is described. The mutated genes, when present on multicopy plasmids, interfered with colony formation by Escherichia coli host strains with a functional chromosomal dnaB gene. The lethal phenotype was expressed specifically in supE (glutamine-inserting) host strains and not in Sup+ strains, because the mutant genes, by design, also possessed an amber mutation derived from a glutamine codon. Mutations located at 11 sites by deletion mapping and DNA sequence analysis varied in the temperature dependence and severity of their lethal effects. None of the mutations complemented a dnaB(Ts) host strain at high temperature (42 degrees C). Therefore, these nonfunctional DnaB proteins must engage some component(s) of the DNA replication machinery and inhibit replication. These mutations are predicted to confer limited, specific defects in either the catalytic activity of DnaB or the ability of DnaB to interact with one of its ligands such as DNA, nucleotide, or another replication protein. The variety of mutant sites and detailed phenotypes represented in this group of mutations may indicate the operation of more than one specific mechanism of lethality.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=211345Documentos Relacionados
- Sequence of the dnaB gene of Salmonella typhimurium.
- Functional characterization of Helicobacter pylori DnaB helicase
- pryB mutations as suppressors of arginine auxotrophy in Salmonella typhimurium.
- The Interaction of Bacteriophage P2 B Protein with Escherichia coli DnaB Helicase
- Illegitimate Recombination Induced by Overproduction of DnaB Helicase in Escherichia coli