title: pH-regulated gene expression of the gastric pathogen Helicobacter pylori.
abstract: Colonization by the gastric pathogen Helicobacter pylori has been shown to be intricately linked to the development of gastritis, ulcers, and gastric malignancy. Little is known about mechanisms employed by the bacterium that help it adapt to the hostile environment of the human stomach. In an effort to extend our knowledge of these mechanisms, we utilized spotted-DNA microarrays to characterize the response of H. pylori to low pH. Expression of approximately 7% of the bacterial genome was reproducibly altered by shift to low pH. Analysis of the differentially expressed genes led to the discovery that acid exposure leads to profound changes in motility of H. pylori, as a larger percentage of acid-exposed bacterial cells displayed motility and moved at significantly higher speeds. In contrast to previous publications, we found that expression of the bacterial virulence gene cagA was strongly repressed by acid exposure. Furthermore, this transcriptional repression was reflected at the level of protein accumulation in the H. pylori cell.
authors.affiliation: Department of Microbiology and Immunology, Stanford School of Medicine, California 94305, USA. dmerrell@stanford.edu
authors.forename: D Scott
authors.initials: DS
authors.lastname: Merrell
authors.forename: Maria L
authors.initials: ML
authors.lastname: Goodrich
authors.forename: Glen
authors.initials: G
authors.lastname: Otto
authors.forename: Lucy S
authors.initials: LS
authors.lastname: Tompkins
authors.forename: Stanley
authors.initials: S
authors.lastname: Falkow
mesh_terms: D000641:Ammonia / Q000378:metabolism; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D005408:Flagellin / Q000096:biosynthesis; D015964:Gene Expression Regulation, Bacterial; D005849:Gerbillinae; D016480:Helicobacter pylori / Q000235:genetics* / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D015854:Up-Regulation
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori; D005408:Flagellin; C067138:flaA protein, bacteria; C416532:flaB flagellin; D000641:Ammonia