A novel relaxase homologue is involved in chromosomal DNA processing for type IV secretion in <i>Neisseria gonorrhoeae</i>

Salgado-Pabón, Wilmara; Jain, Shubham; Turner, Nicholas; Does, Chris van der; Dillard, Joseph P.

doi:10.1111/j.1365-2958.2007.05966.x

Cited by 48 publications

(98 citation statements)

References 63 publications

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“…The ComB system is ancestrally related to the A. tumefaciens VirB/VirD4 system but lacks the Dtr proteins and T4CP substrate receptor required for DNA export (129,130,155). The GGI DNA release system is related to the Escherichia coli F plasmid transfer system and codes for Dtr, T4CP, and Mpf subunits commonly associated with conjugation machines (122,232). The ComB system is unique among known bacterial competence systems in its phylogenetic relatedness to T4SS.…”

Section: Dna Uptake and Release Systemsmentioning

confidence: 99%

“…The relaxase domain of TraI GGI is fused to a phosphohydrolase (HD) domain, whose metal-dependent phosphohydrolase activity might also contribute in some way to the processing reaction. TraI GGI also possesses an N-terminal amphipathic helix that mediates binding to the inner membrane (232). Membrane binding, a property shared by other relaxases and accessory Dtr processing factors, might promote the engagement of the relaxase-DNA intermediate with the T4CP receptor at the membrane (see below).…”

Section: Processing For Dna Release and Uptakementioning

confidence: 99%

“…The N. gonorrhoeae GGI DNA release system encodes a relaxase, termed TraI, that binds and nicks the chromosome at a cognate oriT site within the GGI (232). The relaxase domain of TraI GGI is fused to a phosphohydrolase (HD) domain, whose metal-dependent phosphohydrolase activity might also contribute in some way to the processing reaction.…”

Section: Processing For Dna Release and Uptakementioning

confidence: 99%

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Biological Diversity of Prokaryotic Type IV Secretion Systems

Martı́nez

Christie

2009

Microbiol Mol Biol Rev

623

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: Dna Uptake and Release Systemsmentioning

confidence: 99%

Section: Processing For Dna Release and Uptakementioning

confidence: 99%

Section: Processing For Dna Release and Uptakementioning

confidence: 99%

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Biological Diversity of Prokaryotic Type IV Secretion Systems

Martı́nez

Christie

2009

Microbiol Mol Biol Rev

623

780

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“…The DNA secretion assay was performed as described previously (39). Briefly, piliated (P ϩ ) gonococcal colonies were harvested from a GCB plate and grown for 2 h at 37°C with aeration in GW medium.…”

mentioning

confidence: 99%

“…Our studies have demonstrated that ϳ80% of gonococcal strains carry the genes for a type IV secretion system (T4SS) (11,21). The T4SS transports chromosomal DNA into the extracellular milieu, where the secreted DNA is effective in transforming other gonococci in the population (11,22,39). Thus, type IV secretion functions as a mechanism of DNA donation for natural transformation.…”

mentioning

confidence: 99%

Increased Expression of the Type IV Secretion System in Piliated Neisseria gonorrhoeae Variants

Salgado-Pabón

Hackett

et al. 2010

J Bacteriol

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Neisseria gonorrhoeae produces a type IV secretion system that secretes chromosomal DNA. The secreted DNA is active in the transformation of other gonococci in the population and may act to transfer antibiotic resistance genes and variant alleles for surface antigens, as well as other genes. We observed that gonococcal variants that produced type IV pili secreted more DNA than variants that were nonpiliated, suggesting that the process may be regulated. Using microarray analysis, we found that a piliated strain showed increased expression of the gene for the putative type IV secretion coupling protein TraD, whereas a nonpiliated variant showed increased expression of genes for transcriptional and translational machinery, consistent with its higher growth rate compared to that of the piliated strain. These results suggested that type IV secretion might be controlled by either traD expression or growth rate. A mutant with a deletion in traD was found to be deficient in DNA secretion. Further mutation and complementation analysis indicated that traD is transcriptionally and translationally coupled to traI, which encodes the type IV secretion relaxase. We were able to increase DNA secretion in a nonpiliated strain by inserting a gene cassette with a strong promoter to drive the expression of the putative operon containing traI and traD. Together, these data suggest a model in which the type IV secretion system apparatus is made constitutively, while its activity is controlled through regulation of traD and traI.

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