J Med Microbiol
Department of Biology, College of William and Mary, Williamsburg, VA, USA.
Published: June 2017
Purpose: We investigated the transcription of adhesin-encoding genes sabA, hopZ and labA in Helicobacter pylori strain J99. Each possesses a repeating homopolymeric nucleotide tract within their promoter regions, and sabA and hopZ possess repeats within their 5' coding regions.
Methodology: We altered the repeat lengths associated with the adhesin genes and quantified mRNA levels by real-time quantitative PCR. Using adherence to AGS cells and IL-8 assays, we examined the effects of altered transcript levels. We assessed the role of ArsRS in transcription using an arsS null mutant and by examining ArsR binding to promoter regions via electrophoretic mobility shift assays.
Results: Extensions or truncations of promoter region repeats in hopZ and labA increased transcript levels, mirroring results shown by our lab and others for mutations in the sabA promoter. Altered lengths of the poly-cytosine thymine tract within the 5' coding region of sabA demonstrated that switching from phase-off to phase-on significantly increased mRNA levels. However, mutations in the poly-thymine tract of sabA, which increased mRNA levels, do not behave synergistically with phase-on mutations. Phase-on mutations of sabA resulted in increased H. pylori adherence to AGS cells, but only a modest effect on IL-8. hopZ and labA, and sabA paralogue sabB, transcript levels were increased in an arsS mutant and ArsR bound the promoter regions for each of these genes in vitro.
Conclusion: This work highlights the complex nature of adhesin regulation, its impact on H. pylori attachment and the pervasive role of ArsRS in adhesin expression. Such regulation may help facilitate the decades-long persistence of infection.
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http://dx.doi.org/10.1099/jmm.0.000491 | DOI Listing |
Mol Microbiol
October 2018
Structural and Molecular Microbiology, VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium.
The human stomach pathogen Helicobacter pyloriattaches to healthy and inflamed gastric tissue through members of a paralogous family of 'Helicobacter outer membrane proteins' (Hops), including adhesins BabA, SabA, HopQ, LabA and HopZ. Hops share a conserved 25 kDa C-terminal region that is thought to form an autotransporter-like transmembrane domain. Instead, our results show that Hops contain a non-continuous transmembrane domain, composed of seven predicted β-strands at the C-terminus and one at the N-terminus.
View Article and Find Full Text PDFJ Med Microbiol
June 2017
Department of Biology, College of William and Mary, Williamsburg, VA, USA.
Purpose: We investigated the transcription of adhesin-encoding genes sabA, hopZ and labA in Helicobacter pylori strain J99. Each possesses a repeating homopolymeric nucleotide tract within their promoter regions, and sabA and hopZ possess repeats within their 5' coding regions.
Methodology: We altered the repeat lengths associated with the adhesin genes and quantified mRNA levels by real-time quantitative PCR.
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