Cloning of theHelicobacter pylori recA gene and functional characterization of its product

Schmitt, Wolfgang; Odenbreit, Stefan; Heuermann, Dorothee; Haas, Rainer

doi:10.1007/bf02423452

Cited by 67 publications

(65 citation statements)

References 46 publications

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“…This may reflect the level of expression of the H. pylori genes in E. coli, protein stability, or another factor. One factor that limited RecA protein activity in our experiments may be the reported post-translational modification of H. pylori RecA by glycosylation in H. pylori but not E. coli (73,74). Expression of H. pylori RecA failed to complement the UV sensitivity of an E. coli recA mutant (74).…”

Section: Discussionmentioning

confidence: 98%

Dual Nuclease and Helicase Activities of Helicobacter pylori AddAB Are Required for DNA Repair, Recombination, and Mouse Infectivity

Amundsen

Fero

Salama

et al. 2009

Journal of Biological Chemistry

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Helicobacter pylori infection of the human stomach is associated with disease-causing inflammation that elicits DNA damage in both bacterial and host cells. NUC showed partial attenuation. E. coli ⌬recBCD expressing H. pylori addAB was recombination-deficient unless H. pylori recA was also expressed, suggesting a species-specific interaction between AddAB and RecA and also that H. pylori AddAB participates in both DNA repair and recombination. These results support a role for both the AddAB nuclease and helicase in DNA repair and promoting infectivity.

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Section: Discussionmentioning

confidence: 98%

Dual Nuclease and Helicase Activities of Helicobacter pylori AddAB Are Required for DNA Repair, Recombination, and Mouse Infectivity

Amundsen

Fero

Salama

et al. 2009

Journal of Biological Chemistry

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“…A number of additional proteins not classified as ComB proteins seem to be involved at different steps in the transformation competence process, such as the cytoplasmic proteins RecA (42) and DprA (3,46), the inner-membrane protein ComE3 (53), and the secreted protein ComH (45). The goal of this study was to identify additional components of the T4SS-based ComB DNA uptake machinery.…”

mentioning

confidence: 99%

Functional and Topological Characterization of Novel Components of the comB DNA Transformation Competence System in Helicobacter pylori

Karnholz¹,

Hoefler²,

Odenbreit³

et al. 2006

J Bacteriol

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Helicobacter pylori is one of the most diverse bacterial species known. A rational basis for this genetic variation may be provided by its natural competence for genetic transformation and high-frequency recombination. Many bacterial competence systems have homology with proteins that are involved in the assembly of type IV pili and type II secretion systems. In H. pylori, DNA uptake relies on a transport system related to type IV secretion systems (T4SS) designated the comB system. The prototype of a T4SS in Agrobacterium tumefaciens consists of 11 VirB proteins and VirD4, which form the core unit necessary for the delivery of single proteins or large nucleoprotein complexes into target cells. In the past we identified proteins ComB4 and ComB7 through ComB10 as being involved in the process of DNA uptake in H. pylori. In this study we identified and functionally characterized further (T4SS-homologous) components of the comB transformation competence system. By combining computer prediction modeling, experimental topology determination, generation of knockout strains, and genetic complementation studies we identified ComB2, ComB3, and ComB6 as essential components of the transformation apparatus, structurally and functionally homologous to VirB2, VirB3, and VirB6, respectively. comB2, comB3, and comB4 are organized as a separate operon. Thus, for the H. pylori comB system, all T4SS core components have been identified except for homologues to VirB1, VirD4, VirB5, and VirB11.Helicobacter pylori, a highly motile gram-negative bacterial pathogen, is the principal cause of chronic active gastritis and peptic ulcer disease in humans and has been implicated in the development of gastric mucosa-associated lymphoid tissue lymphoma and adenocarcinoma (38,49). H. pylori colonizes a very special habitat at the surface of gastric epithelial cells or in the mucus layer covering the epithelium, which suggests that this bacterium has evolved specialized features for gastric adaptation. A comparison of the two published genome sequences shows considerable diversity in gene content, with about 7% of all putative genes being strain specific (2). The panmictic population structure of H. pylori is believed to result from frequent recombination during mixed colonization by unrelated strains (20,50).H. pylori is naturally competent for genetic transformation (36). Natural transformation competence in bacteria is a complex process, involving DNA binding, uptake/translocation, and recombination. In general, bacterial competence systems have homology with proteins that are involved in the assembly of type IV pili and type II secretion systems and form a structure that partially spans the cell envelope (see reference 13 for a recent review). In H. pylori, DNA uptake is not mediated by a type IV pilus-based apparatus but relies on a transport system related to type IV secretion systems (T4SS) designated the comB system (26).The Vir system of Agrobacterium tumefaciens, necessary for the transfer of its transferred DNA (T-DNA) into plant ce...

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“…Furthermore, ComB9 was identified as a periplasmic protein attached to the membrane, and the N-terminus of ComB10 seems to be anchored in the cytoplasmic membrane, while the main part of the protein is located in the periplasm [42]. Apart from the ComB system, additional proteins involved at different steps in the transformation competence process have also been identified, such as the cytoplasmatic proteins RecA [43], DprA [44], the secreted protein ComH [45], and the cytoplasmatic channel, ComEC, previously described in Bacillus subtilis [46]. These factors also appear to be essential for DNA uptake in H. pylori.…”

Section: General Role Of Type IV Secretion Systems (T4sss) In Dna Excmentioning

confidence: 99%

DNA transfer in the gastric pathogen Helicobacter pylori

Fernández-González

Backert

2014

J Gastroenterol

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The gastric pathogen Helicobacter pylori is one of the most genetically diverse bacteria. Recombination and DNA transfer contribute to its genetic variability and enhance host adaptation. Among the strategies described to increase genetic diversity in bacteria, DNA transfer by conjugation is one of the best characterized. Using this mechanism, a fragment of DNA from a donor cell can be transferred to a recipient, always mediated by a conjugative nucleoprotein complex, which is evolutionarily related to type IV secretion systems (T4SSs). Interestingly, the H. pylori chromosomes can encode up to four T4SSs, including the cagPAI, comB, tfs3, and tfs4 genes, some of which are known to promote chronic H. pylori infection. The T4SS encoded by the cagPAI mediates the injection of the effector protein CagA and proinflammatory signaling, and the comB system is involved in DNA uptake from the environment. However, the role of tfs3 and tfs4 is not yet clear. The presence of a functional XerD tyrosine recombinase and 5 0 AAAGAATG-3 0 border sequences as well as two putative conjugative relaxases (Rlx1 and Rlx2), a coupling protein (TraG), and a chromosomal region carrying a putative origin of transfer (oriT) suggest the existence of a DNA transfer apparatus in tfs4. Moreover, a conjugation-like DNA transfer mechanism in H. pylori has already been described in vitro, but whether this occurs in vivo is still unknown. Some extrachromosomal plasmids and phages are also present in various H. pylori strains. Genetic exchange among plasmids and chromosomes, and involved DNA mobilization events, could explain part of H. pylori's genetic diversity. Here, we review our knowledge about the possible DNA transfer mechanisms in H. pylori and its implications in bacterial adaptation to the host environment.

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Cloning of theHelicobacter pylori recA gene and functional characterization of its product

Cited by 67 publications

References 46 publications

Dual Nuclease and Helicase Activities of Helicobacter pylori AddAB Are Required for DNA Repair, Recombination, and Mouse Infectivity

Dual Nuclease and Helicase Activities of Helicobacter pylori AddAB Are Required for DNA Repair, Recombination, and Mouse Infectivity

Functional and Topological Characterization of Novel Components of the comB DNA Transformation Competence System in Helicobacter pylori

DNA transfer in the gastric pathogen Helicobacter pylori

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