Open AccessCharacterization of the σ E ‐dependent rpoEp3 promoter of Salmonella enterica serovar Typhimurium
Author(s) -
Skovierova Henrieta,
Rezuchova Bronislava,
Homerova Dagmar,
Roberts Mark,
Kormanec Jan
Publication year - 2006
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2006.00325.x
Subject(s) - regulon , promoter , salmonella enterica , sigma factor , biology , plasmid , consensus sequence , microbiology and biotechnology , nucleotide , nucleic acid sequence , escherichia coli , mutagenesis , genetics , gene , mutation , gene expression , peptide sequence
Using a two‐plasmid system, we recently identified σ E ‐dependent promoters directing expression of the σ E regulon genes in Salmonella enterica serovar Typhimurium ( S . Typhimurium). Comparison of the promoters revealed a consensus sequence almost identical to the σ E ‐dependent rpoEp3 promoter directing expression of rpoE . This two‐plasmid system was previously optimized to identify nucleotides critical for the rpoEp3 promoter activity. However, two highly conserved nucleotides in the σ E consensus sequence were not identified by this screening. In the present study, we have improved the two‐plasmid screening system using a new optimized error‐prone PCR mutagenesis. Together with site‐directed mutagenesis, we further identified nucleotides critical for activity of the rpoEp3 promoter and quantified the effect of the particular mutation upon promoter activity. All the identified critical nucleotides of the rpoEp3 promoter (in capital) were located in the −35 (ggAACtt) and −10 (gTCtaA) regions and corresponded to the most conserved nucleotides in the σ E consensus sequence. The expression of the wild‐type and mutated rpoEp3 promoters was confirmed in S . Typhimurium and was found to exhibit a different pattern of σ E activation compared with Escherichia coli , with a peak rpoEp3 promoter activity in early stationary phase followed by a decrease in late stationary phase.