Neisseria gonorrhoeae secretes chromosomal DNA via a novel type IV secretion system (original) (raw)
Related papers
Functional Analysis of the Gonococcal Genetic Island of Neisseria gonorrhoeae
PLoS ONE, 2014
Neisseria gonorrhoeae is an obligate human pathogen that is responsible for the sexually-transmitted disease gonorrhea. N. gonorrhoeae encodes a T4SS within the Gonococcal Genetic Island (GGI), which secretes ssDNA directly into the external milieu. Type IV secretion systems (T4SSs) play a role in horizontal gene transfer and delivery of effector molecules into target cells. We demonstrate that GGI-like T4SSs are present in other b-proteobacteria, as well as in aand c-proteobacteria. Sequence comparison of GGI-like T4SSs reveals that the GGI-like T4SSs form a highly conserved unit that can be found located both on chromosomes and on plasmids. To better understand the mechanism of DNA secretion by N. gonorrhoeae, we performed mutagenesis of all genes encoded within the GGI, and studied the effects of these mutations on DNA secretion. We show that genes required for DNA secretion are encoded within the yaa-atlA and parA-parB regions, while genes encoded in the yfeB-exp1 region could be deleted without any effect on DNA secretion. Genes essential for DNA secretion are encoded within at least four different operons.
Gene, 1998
A 960-bp ORF potentially encoding a site-specific recombinase has been cloned from Neisseria gonorrhoeae MS11-A. This ORF was designated piv Ng on the basis of similarity of the deduced amino acid sequence to the Piv proteins of Moraxella spp. that are site-specific invertases. Southern hybridization and sequence analysis revealed that there were multiple copies of piv Ng sequence within the genomes of N. gonorrhoeae strains tested, but not in several other neisserial species. Southern hybridization and sequence analysis further suggested that piv Ng sequences may be associated with genomic rearrangements.
Genetic Manipulation ofNeisseria gonorrhoeae
Current protocols in microbiology, 2011
The sexually-transmitted pathogen, Neisseria gonorrhoeae, undergoes natural transformation at high frequency. This property has led to the rapid dissemination of antibiotic resistance markers and to the panmictic structure of the gonococcal population. However, high frequency transformation also makes N. gonorrhoeae one of the easiest bacterial species to manipulate genetically in the laboratory. Techniques have been developed that result in transformation frequencies >50%, allowing the identification of mutants by screening and without selection. Constructs have been created to take advantage of this high frequency transformation, facilitating genetic mutation, complementation, and heterologous gene expression. Techniques are described for genetic manipulation of N. gonorrhoeae, as well as for growth of this fastidious organism.
Infection and Immunity, 2011
Neisseria gonorrhoeae has been shown to produce biofilms both in experimental flow chambers and in the human host. Our laboratory has shown that extracellular DNA is an essential component of the gonococcal matrix. We have also identified a gene in N. gonorrhoeae , which we designated nuc . This gene has homology with the staphylococcus-secreted thermonuclease. Our laboratory has characterized nuc through phenotypic analysis of a nuc deletion mutant. Biofilms grown with this strain are significantly thicker and of greater biomass than the N. gonorrhoeae 1291 parent strain. Confocal microscopy indicates that the increased size of the mutant biofilms appears to be due to elevated amounts of extracellular DNA in the biofilm matrix. Chromosomal complementation of the nuc mutation restored the wild-type biofilm phenotype. In addition, we have cloned and expressed the Nuc protein in Escherichia coli , and our data indicate that it has the ability to digest multiple forms of DNA and is a t...
Frontiers in Microbiology
Natural transformation, or the uptake of naked DNA from the external milieu by bacteria, holds a unique place in the history of biology. This is both the beginning of the realization of the correct chemical nature of genes and the first technical step to the molecular biology revolution that sees us today able to modify genomes almost at will. Yet the mechanistic understanding of bacterial transformation still presents many blind spots and many bacterial systems lag behind power horse model systems like Escherichia coli in terms of ease of genetic modification. Using Neisseria gonorrhoeae as a model system and using transformation with multiple DNA molecules, we tackle in this paper both some aspects of the mechanistic nature of bacterial transformation and the presentation of new molecular biology techniques for this organism. We show that similarly to what has been demonstrated in other naturally competent bacteria, Neisseria gonorrhoeae can incorporate, at the same time, differen...
Journal of Bacteriology, 2001
We created plasmids for use in insertion-duplication mutagenesis (IDM) of Neisseria gonorrhoeae. This mutagenesis method has the advantage that it requires only a single cloning step prior to transformation into gonococci. Chromosomal DNA cloned into the plasmid directs insertion into the chromosome at the site of homology by a single-crossover (Campbell-type) recombination event. Two of the vectors contain an erythromycin resistance gene, ermC, with a strong promoter and in an orientation such that transcription will proceed into the cloned insert. Thus, these plasmids can be used to create insertions that are effectively nonpolar on the transcription of downstream genes. In addition to the improved ermC, the vector contains two copies of the neisserial DNA uptake sequence to facilitate high-frequency DNA uptake during transformation. Using various chromosomal DNA insert sizes, we have determined that even small inserts can target insertion mutation by this method and that the insertions are stably maintained in the gonococcal chromosome. We have used IDM to create knockouts in two genes in the gonococcal genetic island (GGI) and to clone additional regions of the GGI by a chromosome-walking procedure. Phenotypic characterization of traG and traH mutants suggests a role for the encoded proteins in DNA secretion by a novel type IV secretion system.
Plasmid-mediated chromosomal gene transfer in Neisseria gonorrhoeae
Journal of Bacteriology, 1978
An indigenous Neisseria gonorrhoeae conjugative plasmid, pLE2450, was tested for its ability to mediate chromosomal gene transfer between gonococcal strains. Plasmid-mediated chromosomal transfer was detected at a low frequency and can be used to establish certain linkage relationships between amino acid and antibiotic resistance markers.