Genetic Manipulation of a Naturally Competent Bacterium, Helicobacter pylori

ABSTRACT Many Helicobacter pylori genetic studies would benefit from an ability to move DNA sequences easily between strains by transformation and homologous recombination, without needing to leave a conventional drug resistance determinant at the targeted locus. Presented here is a two-gene cassette that can be selected both (i) against, due to a Campylobacter jejuni rpsL gene (dominant streptomycin susceptibility in cells also carrying an rpsL-str r allele), and (ii) for, due to an erm gene (erythromycin resistance). This rpsL,erm cassette's utility was assessed by using it to replace four gene loci (mdaB, frxA, fur, and nikR) in four streptomycin-resistant [Strr] strain backgrounds (derivatives of 26695, SS1, X47, and G27MA). The resultant 16 strains (phenotypically erythromycin resistant [Ermr] and Strs) were each transformed with wild-type genomic DNAs, and Strr derivatives were selected. The desired Erms Strr isolates were obtained at frequencies that ranged from 17 to 96% among Strr transformants, with the Erms yield apparently depending on the strain background and genome location of the targeted locus. The ease of isolating unmarked transformants described here should be valuable for many H. pylori molecular genetic and evolutionary analyses.

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Expression of Helicobacter pylori Vacuolating Toxin in Escherichia coli

Infection and Immunity ◽

10.1128/iai.71.4.2266-2271.2003 ◽

2003 ◽

Vol 71 (4) ◽

pp. 2266-2271 ◽

Cited By ~ 10

Author(s):

Mark S. McClain ◽

Timothy L. Cover

Keyword(s):

Escherichia Coli ◽

Helicobacter Pylori ◽

Peptic Ulcer ◽

Genetic Manipulation ◽

Expression System ◽

Structure And Function ◽

Heterologous Expression System ◽

Efficient System ◽

Ulcer Disease ◽

And Function

ABSTRACT VacA is a secreted toxin that plays a role in Helicobacter pylori colonization of the stomach and that contributes to the pathogenesis of peptic ulcer disease. Studies of VacA structure and function have been hindered by the lack of an efficient system for expression and genetic manipulation of this toxin. In this study, we developed methodology for expression of a functionally active VacA toxin in Escherichia coli. We then used a high-throughput screen to analyze a library of mutant toxins with pentapeptide insertions and identified six mutants that lacked the capacity to induce vacuolation of HeLa cells. The capacity to analyze VacA in this heterologous-expression system should greatly facilitate efforts to elucidate the structure and function of this toxin.

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Genetic Manipulation of Helicobacter pylori Virulence Function by Host Carcinogenic Phenotypes

Cancer Research ◽

10.1158/0008-5472.can-16-2922 ◽

2017 ◽

Vol 77 (9) ◽

pp. 2401-2412 ◽

Cited By ~ 12

Author(s):

Giovanni Suarez ◽

Judith Romero-Gallo ◽

Johanna C. Sierra ◽

M. Blanca Piazuelo ◽

Uma S. Krishna ◽

...

Keyword(s):

Helicobacter Pylori ◽

Genetic Manipulation

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The rod-to-coccoid body transformation in cultures of Helicobacter pylori

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100160686 ◽

1990 ◽

Vol 48 (3) ◽

pp. 626-627

Author(s):

A. R. Crooker ◽

W. G. Kraft ◽

T. L. Beard ◽

M. C. Myers

Keyword(s):

Helicobacter Pylori ◽

Growth Cycle ◽

Negative Bacterium ◽

Body Formation ◽

Coccoid Form ◽

Spiral Form ◽

Prolonged Culture ◽

H Pylori ◽

Upper Gastrointestinal

Helicobacter pylori is a microaerophilic, gram-negative bacterium found in the upper gastrointestinal tract of humans. There is strong evidence that H. pylori is important in the etiology of gastritis; the bacterium may also be a major predisposing cause of peptic ulceration. On the gastric mucosa, the organism exists as a spiral form with one to seven sheathed flagella at one (usually) or both poles. Short spirals were seen in the first successful culture of the organism in 1983. In 1984, Marshall and Warren reported a coccoid form in older cultures. Since that time, other workers have observed rod and coccal forms in vitro; coccoid forms predominate in cultures 3-7 days old. We sought to examine the growth cycle of H. pylori in prolonged culture and the mode of coccoid body formation.

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Metabolic engineering of CHO cells to prepare glycoproteins

Emerging Topics in Life Sciences ◽

10.1042/etls20180056 ◽

2018 ◽

Vol 2 (3) ◽

pp. 433-442 ◽

Cited By ~ 1

Author(s):

Qiong Wang ◽

Michael J. Betenbaugh

Keyword(s):

Metabolic Engineering ◽

Cho Cells ◽

Genetic Manipulation ◽

Chinese Hamster ◽

Post Translational Modification ◽

Effector Functions ◽

Recombinant Glycoproteins ◽

Production Platform ◽

Chemical Inhibitors ◽

Amino Acid Mutations

As a complex and common post-translational modification, N-linked glycosylation affects a recombinant glycoprotein's biological activity and efficacy. For example, the α1,6-fucosylation significantly affects antibody-dependent cellular cytotoxicity and α2,6-sialylation is critical for antibody anti-inflammatory activity. Terminal sialylation is important for a glycoprotein's circulatory half-life. Chinese hamster ovary (CHO) cells are currently the predominant recombinant protein production platform, and, in this review, the characteristics of CHO glycosylation are summarized. Moreover, recent and current metabolic engineering strategies for tailoring glycoprotein fucosylation and sialylation in CHO cells, intensely investigated in the past decades, are described. One approach for reducing α1,6-fucosylation is through inhibiting fucosyltransferase (FUT8) expression by knockdown and knockout methods. Another approach to modulate fucosylation is through inhibition of multiple genes in the fucosylation biosynthesis pathway or through chemical inhibitors. To modulate antibody sialylation of the fragment crystallizable region, expressions of sialyltransferase and galactotransferase individually or together with amino acid mutations can affect antibody glycoforms and further influence antibody effector functions. The inhibition of sialidase expression and chemical supplementations are also effective and complementary approaches to improve the sialylation levels on recombinant glycoproteins. The engineering of CHO cells or protein sequence to control glycoforms to produce more homogenous glycans is an emerging topic. For modulating the glycosylation metabolic pathways, the interplay of multiple glyco-gene knockouts and knockins and the combination of multiple approaches, including genetic manipulation, protein engineering and chemical supplementation, are detailed in order to achieve specific glycan profiles on recombinant glycoproteins for superior biological function and effectiveness.

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