Plasticity of Repetitive DNA Sequences within a Bacterial (Type IV) Secretion System Component

Aras, Rahul; Fischer, Wolfgang; Perez-Perez, Guillermo I.; Crosatti, Marialuisa; Ando, Takafumi; Haas, Rainer; Blaser, Martin J.

doi:10.1084/jem.20030381

Cited by 88 publications

(95 citation statements)

References 66 publications

(111 reference statements)

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“…Most interesting are CagT and CagY, two subunits reported to be similar to the A. tumefaciens core subunits VirB7 and VirB10, respectively. However, CagT and CagY are considerably larger than their VirB counterparts, both localize extracellularly as a component of a large sheathed filament produced by the Cag T4SS, and both possess variable-or multiple-repeat regions (8,227). Among Cag systems of different H. pylori isolates, repeat regions of these subunits display considerable variation in size and composition.…”

Section: Evolution Of T4ss-associated Surface Structuresmentioning

confidence: 99%

Biological Diversity of Prokaryotic Type IV Secretion Systems

Martı́nez

Christie

2009

Microbiol Mol Biol Rev

618

780

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SUMMARY Type IV secretion systems (T4SS) translocate DNA and protein substrates across prokaryotic cell envelopes generally by a mechanism requiring direct contact with a target cell. Three types of T4SS have been described: (i) conjugation systems, operationally defined as machines that translocate DNA substrates intercellularly by a contact-dependent process; (ii) effector translocator systems, functioning to deliver proteins or other macromolecules to eukaryotic target cells; and (iii) DNA release/uptake systems, which translocate DNA to or from the extracellular milieu. Studies of a few paradigmatic systems, notably the conjugation systems of plasmids F, R388, RP4, and pKM101 and the Agrobacterium tumefaciens VirB/VirD4 system, have supplied important insights into the structure, function, and mechanism of action of type IV secretion machines. Information on these systems is updated, with emphasis on recent exciting structural advances. An underappreciated feature of T4SS, most notably of the conjugation subfamily, is that they are widely distributed among many species of gram-negative and -positive bacteria, wall-less bacteria, and the Archaea. Conjugation-mediated lateral gene transfer has shaped the genomes of most if not all prokaryotes over evolutionary time and also contributed in the short term to the dissemination of antibiotic resistance and other virulence traits among medically important pathogens. How have these machines adapted to function across envelopes of distantly related microorganisms? A survey of T4SS functioning in phylogenetically diverse species highlights the biological complexity of these translocation systems and identifies common mechanistic themes as well as novel adaptations for specialized purposes relating to the modulation of the donor-target cell interaction.

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Section: Evolution Of T4ss-associated Surface Structuresmentioning

confidence: 99%

Biological Diversity of Prokaryotic Type IV Secretion Systems

Martı́nez

Christie

2009

Microbiol Mol Biol Rev

618

780

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“…H. pylori also suppresses T cell proliferation and activation and induces selective T cell apoptosis, again partially through specific VacA effects on signaling (49, 73, S64-S66). It evades host adaptive responses by mimicry of the gastric epithelial fucosylated (Lewis) antigens (74, S67), and by antigenic variation of surface proteins including a critical pilus molecule, CagY (75). As this high-frequency antigenic variation occurs through mutation (usually slipped-strand mispairing) and intragenomic recombination between homologous sequences (19,23, S9, S68), these genetic mechanisms are important contributors to immune evasion.…”

Section: Immune Evasion and Manipulation By H Pylorimentioning

confidence: 99%

Helicobacter pylori persistence: biology and disease

Blaser¹,

Atherton²

2004

J. Clin. Invest.

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768

540

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Helicobacter pylori are bacteria that have coevolved with humans to be transmitted from person to person and to persistently colonize the stomach. Their population structure is a model for the ecology of the indigenous microbiota. A well-choreographed equilibrium between bacterial effectors and host responses permits microbial persistence and health of the host but confers risk of serious diseases, including peptic ulceration and gastric neoplasia.

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“…Computational analysis of the fully sequenced H. pylori strains 26695 and J99 also has identified a large number of direct DNA repeats (1,6,54). Intragenomic recombination between such repeats allows deletion or duplication of intervening DNA segments, generating novel subtypes with changes in virulence effectors, such as CagA and CagY, and alterations in restriction modification systems (5,7,8).…”

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confidence: 99%

Effect of Host Species on RecG Phenotypes in Helicobacter pylori and Escherichia coli

et al. 2004

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Recombination is a fundamental mechanism for the generation of genetic variation. Helicobacter pylori strains have different frequencies of intragenomic recombination, arising from deletions and duplications between DNA repeat sequences, as well as intergenomic recombination, facilitated by their natural competence. We identified a gene, hp1523, that influences recombination frequencies in this highly diverse bacterium and demonstrate its importance in maintaining genomic integrity by limiting recombination events. HP1523 shows homology to RecG, an ATP-dependent helicase that in Escherichia coli allows repair of damaged replication forks to proceed without recourse to potentially mutagenic recombination. Cross-species studies done show that hp1523 can complement E. coli recG mutants in trans to the same extent as E. coli recG can, indicating that hp1523 has recG function. The E. coli recG gene only partially complements the hp1523 mutation in H. pylori. Unlike other recG homologs, hp1523 is not involved in DNA repair in H. pylori, although it has the ability to repair DNA when expressed in E. coli. Therefore, host context appears critical in defining the function of recG. The fact that in E. coli recG phenotypes are not constant in other species indicates the diverse roles for conserved recombination genes in prokaryotic evolution.

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Plasticity of Repetitive DNA Sequences within a Bacterial (Type IV) Secretion System Component

Cited by 88 publications

References 66 publications

Biological Diversity of Prokaryotic Type IV Secretion Systems

Biological Diversity of Prokaryotic Type IV Secretion Systems

Helicobacter pylori persistence: biology and disease

Effect of Host Species on RecG Phenotypes in Helicobacter pylori and Escherichia coli

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