Open AccessTranscriptional and mutational analysis of the Helicobacter pylori urease promoter
Author(s) -
Davies Beverly J.,
Vries Nicolette,
Rijpkema Sjoerd G.,
Vliet Arnoud H.M.,
Penn Charles W.
Publication year - 2002
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.1574-6968.2002.tb11281.x
Subject(s) - operon , promoter , biology , gene , urease , transcription (linguistics) , lac operon , reporter gene , genetics , microbiology and biotechnology , gene expression , mutant , enzyme , biochemistry , linguistics , philosophy
Urease is an essential virulence factor of the human gastric pathogen Helicobacter pylori , and is expressed to very high levels. The promoter of the urease operon contains sequences resembling the canonical −10 and extended −10 motifs, but no discernible −35 motif. To establish the role of different motifs and regions in the urease promoter, we fused the urease promoter to a genomic lacZ reporter gene in H. pylori , made substitutions in the aforementioned promoter motifs, and also made deletions in the upstream sequences removing regulatory sequences. Substitutions in the −10, extended −10 and predicted −35 motifs all significantly altered expression of the lacZ reporter gene, demonstrating their importance in transcription of the H. pylori urease operon. In contrast, sequential deletions upstream of the −35 region did not affect expression of the lacZ reporter gene. This demonstrates the modular structure of the H. pylori urease promoter, where basal levels of transcription are initiated from a typical σ 70 promoter, which requires −10 and extended −10 motifs, and also its −35 motif for efficient transcription. Upstream sequences are not involved in basal levels of urease transcription, but play an important role in responses to environmental stimuli like nickel.