pH-Regulated Gene Expression of the Gastric Pathogen<i>Helicobacter pylori</i>

Merrell, D. Scott; Goodrich, Maria L.; Otto, G; Tompkins, Lucy S.; Falkow, Stanley

doi:10.1128/iai.71.6.3529-3539.2003

Cited by 212 publications

(294 citation statements)

References 83 publications

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“…TL% is the ratio of VSL to VCL multiplied by 100. Acid increased the VCL of H. pylori strains mG27m and SS1, as reported before for H. pylori (Merrell et al, 2003;Sidebotham et al, 2003) (Fig. 1a).…”

Section: H Pylori Temporal Swimming Assays Work Optimally With Fbs Asupporting

confidence: 68%

A supplemented soft agar chemotaxis assay demonstrates the Helicobacter pylori chemotactic response to zinc and nickel

2013

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Department of Microbiology and Environmental Toxicology at the University of California at Santa Cruz, Santa Cruz, CA, USA Directed motility, or chemotaxis, is required for Helicobacter pylori to establish infection in the stomach, although the full repertoire of this bacterium's chemotactic responses is not yet known. Here we report that H. pylori responds to zinc as an attractant and nickel as a repellent. To reach this conclusion, we employed both a temporal chemotaxis assay based on bacterial reversals and a supplemented soft agar spatial assay. We refined the temporal assay using a previously described chemorepellent, acid, and found that H. pylori requires rich media with serum to maintain optimal swimming motility. Surprisingly, we found that some strains respond to acid as an attractant, and that the TlpC chemoreceptor correlated with whether acid was sensed as an attractant or repellent. Using this same assay, we detected weak repellent responses to nickel and copper, and a varied response to zinc. We thus developed an alternative spatial chemotactic assay called the supplemented soft agar assay, which utilizes soft agar medium supplemented with the test compound. With Escherichia coli, the attractant serine slowed overall bacterial migration, while the repellent nickel increased the speed of overall migration. In H. pylori we detected slowed migration with doubled tryptone media, as well as zinc, consistent with an attractant response. In contrast, nickel increased migration, consistent with repulsion.

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Section: H Pylori Temporal Swimming Assays Work Optimally With Fbs Asupporting

confidence: 68%

A supplemented soft agar chemotaxis assay demonstrates the Helicobacter pylori chemotactic response to zinc and nickel

2013

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“…While some studies report the up-regulation of flagellar genes under conditions of acid stress (37,53,57,90), others report the down-regulation of these genes (18,84,90). Furthermore, these data remain difficult to interpret, as only a subset of the flagellar genes is ever found to be differentially expressed.…”

Section: Discussionmentioning

confidence: 66%

Identification of Campylobacter jejuni Genes Contributing to Acid Adaptation by Transcriptional Profiling and Genome-Wide Mutagenesis

Reid

Pandey

Palyada

et al. 2008

Appl Environ Microbiol

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In order to cause disease, the food-and waterborne pathogen Campylobacter jejuni must face the extreme acidity of the host stomach as well as cope with pH fluctuations in the intestine. In the present study, C. jejuni NCTC 11168 was grown under mildly acidic conditions mimicking those encountered in the intestine. The resulting transcriptional profiles revealed how this bacterium fine-tunes gene expression in response to acid stress. This adaptation involves the differential expression of respiratory pathways, the induction of genes for phosphate transport, and the repression of energy generation and intermediary metabolism genes. We also generated and screened a transposon-based mutant library to identify genes required for wild-type levels of growth under mildly acidic conditions. This screen highlighted the important role played by cell surface components (flagella, the outer membrane, capsular polysaccharides, and lipooligosaccharides) in the acid stress response of C. jejuni. Our data also revealed that a limited correlation exists between genes required for growth under acidic conditions and genes differentially expressed in response to acid. To gain a comprehensive picture of the acid stress response of C. jejuni, we merged transcriptional profiles obtained from acid-adapted cells and cells subjected to acid shock. Genes encoding the transcriptional regulator PerR and putative oxidoreductase subunits Cj0414 and Cj0415 were among the few up-regulated under both acid stress conditions. As a Cj0415 mutant was acid sensitive, it is likely that these genes are crucial to the acid stress response of C. jejuni and consequently are important for host colonization.

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“…With the discovery of H. pylori and other gastric helicobacters, and subsequent insight into the mechanisms by which these organisms adapt to the gastric environment (22), the existence of a bacterial community adapted to this human niche became more plausible. Despite the potential importance of a gastric microbial community in human health and disease, few data on the complexity of this biota have been available.…”

Section: Discussionmentioning

confidence: 99%

Molecular analysis of the bacterial microbiota in the human stomach

Bik

Eckburg

Gill

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

954

850

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The microbiota of the human stomach and the influence of Helicobacter pylori colonization on its composition remain largely unknown. We characterized bacterial diversity within the human gastric mucosa by using a small subunit 16S rDNA clone library approach and analyzed 1,833 sequences generated by broad-range bacterial PCR from 23 gastric endoscopic biopsy samples. A diverse community of 128 phylotypes was identified, featuring diversity at this site greater than previously described. The majority of sequences were assigned to the Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, and Fusobacteria phyla. Ten percent of the phylotypes were previously uncharacterized, including a Deinococcus-related organism, relatives of which have been found in extreme environments but not reported before in humans. The gastric clone libraries from 19 subjects contained H. pylori rDNA; however, only 12 of these subjects tested positive for H. pylori by conventional laboratory methods. Statistical analysis revealed a large degree of intersubject variability of the gastric ecosystem. The presence of H. pylori did not affect the composition of the gastric community. This gastric bacterial rDNA data set was significantly different from sequence collections of the human mouth and esophagus described in other studies, indicating that the human stomach may be home to a distinct microbial ecosystem. The gastric microbiota may play important, as-yet-undiscovered roles in human health and disease.

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pH-Regulated Gene Expression of the Gastric PathogenHelicobacter pylori

Cited by 212 publications

References 83 publications

A supplemented soft agar chemotaxis assay demonstrates the Helicobacter pylori chemotactic response to zinc and nickel

A supplemented soft agar chemotaxis assay demonstrates the Helicobacter pylori chemotactic response to zinc and nickel

Identification of Campylobacter jejuni Genes Contributing to Acid Adaptation by Transcriptional Profiling and Genome-Wide Mutagenesis

Molecular analysis of the bacterial microbiota in the human stomach

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