Novel determinant (comA) essential for natural transformation competence in Neisseria gonorrhoeae and the effect of a comA defect on pilin variation

Facius, Dirk; Meyer, Thomas F.

doi:10.1111/j.1365-2958.1993.tb00942.x

Cited by 84 publications

(79 citation statements)

References 58 publications

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“…ComA is essential for transport of DNA through the cytoplasmic membrane but does not affect DNA uptake into the periplasm (28). We found that the force-dependent velocity was independent of comA ( Fig.…”

Section: The Velocity Vs Force Relationship Is In Agreement With Amentioning

confidence: 51%

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Kinetics of DNA uptake during transformation provide evidence for a translocation ratchet mechanism

Hepp

Maier

2016

Proc. Natl. Acad. Sci. U.S.A.

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Horizontal gene transfer can speed up adaptive evolution and support chromosomal DNA repair. A particularly widespread mechanism of gene transfer is transformation. The initial step to transformation, namely the uptake of DNA from the environment, is supported by the type IV pilus system in most species. However, the molecular mechanism of DNA uptake remains elusive. Here, we used singlemolecule techniques for characterizing the force-dependent velocity of DNA uptake by Neisseria gonorrhoeae. We found that the DNA uptake velocity depends on the concentration of the periplasmic DNA-binding protein ComE, indicating that ComE is directly involved in the uptake process. The velocity-force relation of DNA uptake is in very good agreement with a translocation ratchet model where binding of chaperones in the periplasm biases DNA diffusion through a membrane pore in the direction of uptake. The model yields a speed of DNA uptake of 900 bp·s −1 and a reversal force of 17 pN. Moreover, by comparing the velocityforce relation of DNA uptake and type IV pilus retraction, we can exclude pilus retraction as a mechanism for DNA uptake. In conclusion, our data strongly support the model of a translocation ratchet with ComE acting as a ratcheting chaperone.

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Section: The Velocity Vs Force Relationship Is In Agreement With Amentioning

confidence: 51%

“…In N. gonorrhoeae and other competent species, transport through the outer membrane is uncoupled from transport through the inner membrane (25)(26)(27). Single-stranded DNA is transported through a pore formed by ComA through the inner membrane (28). The probability of DNA uptake is strongly enhanced by the presence of the DNA uptake sequence (DUS) (29).…”

mentioning

confidence: 97%

Kinetics of DNA uptake during transformation provide evidence for a translocation ratchet mechanism

Hepp

Maier

2016

Proc. Natl. Acad. Sci. U.S.A.

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“…In addition to beta-lactamases, a number of other proteins are known to contain the metallobeta-lactamase domain, including thiolesterases that belong to the glyoxalase II family and catalyze the hydrolysis of S-Dlactoyl-glutathione to generate glutathione and D-lactic acid (2). In Neisseria gonorrhoeae, a competence protein required for natural transformation likely is a transporter involved in DNA uptake and also has this domain (10). If vicX encodes a DNA transporter similar to that in N. gonorrhoeae, we would expect a vicX null mutant to show decreased transformability.…”

Section: Discussionmentioning

confidence: 99%

The Streptococcus mutans vicX Gene Product Modulates gtfB / C Expression, Biofilm Formation, Genetic Competence, and Oxidative Stress Tolerance

et al. 2007

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Streptococcus mutans is considered one of the primary etiologic agents of dental caries. Previously, we characterized the VicRK two-component signal transduction system, which regulates multiple virulence factors of S. mutans. In this study, we focused on the vicX gene of the vicRKX tricistronic operon. To characterize vicX, we constructed a nonpolar deletion mutation in the vicX coding region in S. mutans UA159. The growth kinetics of the mutant (designated SmuvicX) showed that the doubling time was longer and that there was considerable sensitivity to paraquat-induced oxidative stress. Supplementing a culture of the wild-type UA159 strain with paraquat significantly increased the expression of vicX (P < 0.05, as determined by analysis of variance [ANOVA]), confirming the role of this gene in oxidative stress tolerance in S. mutans. Examination of mutant biofilms revealed architecturally altered cell clusters that were seemingly denser than the wild-type cell clusters. Interestingly, vicX-deficient cells grown in a glucose-supplemented medium exhibited significantly increased glucosyltransferase B/C (gtfB/C) expression compared with the expression in the wild type (P < 0.05, as determined by ANOVA). Moreover, a sucrose-dependent adhesion assay performed using an S. mutans GS5-derived vicX null mutant demonstrated that the adhesiveness of this mutant was enhanced compared with that of the parent strain and isogenic mutants of the parent strain lacking gtfB and/or gtfC. Also, disruption of vicX reduced the genetic transformability of the mutant approximately 10-fold compared with that of the parent strain (P < 0.05, as determined by ANOVA). Collectively, these findings provide insight into important phenotypes controlled by the vicX gene product that can impact S. mutans pathogenicity.

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“…While the first step requires functional pili (15), the second step depends on comA and is strongly facilitated by exbB (17). The polytopic membrane protein ComA and its orthologs are key components of the DNA transmembrane translocation machinery of other transformable organisms, like N. gonorrhoeae (13), H. influenzae (9), B. subtilis (19), and S. pneumoniae (30). ComA protein is thought to form the pore through which a single strand derived from duplex transforming DNA by degradation of one strand by an unknown DNase reaches the cytoplasm (12).…”

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confidence: 99%

Pseudomonas stutzeri Has Two Closely Related pilA Genes (Type IV Pilus Structural Protein) with Opposite Influences on Natural Genetic Transformation

Graupner

Wackernagel

2001

J Bacteriol

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Pseudomonas stutzeri has type IV pili for which the pilA gene (here termed pilAI) provides the structural protein and which are required for DNA uptake and natural genetic transformation. Downstream of pilAI we identified a gene, termed pilAII, coding for a deduced protein with a size similar to that of PilAI with 55% amino acid sequence identity and with a typical leader peptide including a leader peptidase cleavage site. Fusions to lacZ revealed that pilAII is expressed only about 10% compared to pilAI, although the genes are cotranscribed as shown by reverse transcription-PCR. Surprisingly, insertional inactivation of pilAII produced a hypertransformation phenotype giving about 16-fold-increased transformation frequencies. Hypertransformation also occurred in pilAI pilAII double mutants expressing heterologous pilA genes of nontransformable bacteria, like Pseudomonas aeruginosa or Dichelobacter nodosus. The overexpression of pilAII decreased transformation up to 5,000-fold compared to that of the pilAII mutant. However, neither inactivation of pilAII nor its overexpression affected the amounts of [ 3 H]thymidine-labeled DNA that were competence-specifically bound and taken up by the cells. In the pilAII mutant, the transformation by purified single-stranded DNA (which depends on comA and exbB, as does transformation by duplex DNA) was also increased 17-fold. It is concluded that PilAII suppresses a step in transformation after the uptake of duplex DNA into the cell and perhaps before its translocation into the cytoplasm. The idea that the degree of the transformability of cells could be permanently adjusted by the expression level of an antagonistic protein is discussed.The gram-negative bacterium Pseudomonas stutzeri is ubiquitous and lives in terrestrial habitats and freshwater and marine environments. It is among the species capable of natural genetic transformation (7,21). This horizontal gene transfer mechanism involves the active uptake of free DNA by the cell from the environment and the heritable incorporation of its informational content into the genome. Transformation is thought to contribute to adaptation of populations to a changing environment and thereby to evolution and speciation (12,21). Recently it was shown by electron microscopy that cells of P. stutzeri strain JM300 have type IV pili (15), which are found in a large number of diverse gram-negative bacteria (18, 41). Type IV pili can mediate the interaction of bacteria with surfaces, including those of epithelial cells, and may allow the flagellum-independent translocation of bacteria on solid surfaces, such as on agar medium (41, 45). The phenomenon was termed twitching motility and has been observed in about 20 species, including P. stutzeri (5,18,41,45). Mutations preventing pilus formation abolished twitching motility in P. stutzeri (15). It was also found that the pili allow the infection of P. stutzeri by the pilus-specific phage PO4 (15), which was initially isolated with Pseudomonas aeruginosa as a host (4). Several genes involved ...

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Novel determinant (comA) essential for natural transformation competence in Neisseria gonorrhoeae and the effect of a comA defect on pilin variation

Cited by 84 publications

References 58 publications

Kinetics of DNA uptake during transformation provide evidence for a translocation ratchet mechanism

Kinetics of DNA uptake during transformation provide evidence for a translocation ratchet mechanism

The Streptococcus mutans vicX Gene Product Modulates gtfB / C Expression, Biofilm Formation, Genetic Competence, and Oxidative Stress Tolerance

Pseudomonas stutzeri Has Two Closely Related pilA Genes (Type IV Pilus Structural Protein) with Opposite Influences on Natural Genetic Transformation

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