Open AccessCharacterization of Helicobacter pylori σ 54 promoter‐binding activity
Author(s) -
Pereira Lara E.,
Brahmachary Priyanka,
Hoover Timothy R.
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.1574-6968.2006.00258.x
Subject(s) - promoter , microbiology and biotechnology , sigma factor , transcription (linguistics) , rna polymerase , mutant , activator (genetics) , biology , gene , gene expression , escherichia coli , chemistry , genetics , linguistics , philosophy
Several Helicobacter pylori flagellar genes require σ 54 for their transcription. Predicted H. pylori σ 54 ‐dependent promoters display a preference for A at position −23 instead of C or T as occurs in promoters from most other bacteria. Substitution of the A at position −23 of the H. pylori flaB promoter with a C did not effect expression of a flaB ′ – ′ xylE reporter gene in H. pylori , whereas T or G substitutions at this position drastically reduced expression. Results of gel mobility shift assays that used DNA probes corresponding to core promoter sequences and a H. pylori σ 54 protein fused to the Escherichia coli maltose‐binding protein suggested that H. pylori σ 54 has a higher affinity for promoters with an A at the −23 position. The failure to observe an effect on expression for the flaB mutant promoter with the A to C substitution at the −23 position indicates that sequences flanking the core promoter region may assist binding of H. pylori σ 54 to the mutant flaB promoter. Alternatively, H. pylori RNA polymerase or the σ 54 ‐dependent activator FlgR may compensate for the reduced affinity of σ 54 for the mutant flaB promoter.