Natural genetic transformation of Pseudomonas stutzeri by sand-adsorbed DNA

1990 ◽  
Vol 154 (4) ◽  
pp. 380-385 ◽  
Author(s):  
Michael G. Lorenz ◽  
Wilfried Wackernagel
Keyword(s):  
Genetic Transformation ◽  
Pseudomonas Stutzeri ◽  
Natural Genetic Transformation

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

2001 ◽  
Vol 183 (7) ◽  
pp. 2359-2366 ◽  
Author(s):  
Stefan Graupner ◽  
Wilfried Wackernagel
Keyword(s):  
Genetic Transformation ◽  
Pseudomonas Stutzeri ◽  
Leader Peptide ◽  
Duplex Dna ◽  
Dna Uptake ◽  
Structural Protein ◽  
Dichelobacter Nodosus ◽  
Type Iv ◽  
Insertional Inactivation ◽  
Natural Genetic Transformation

ABSTRACT 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 pilAIwe 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 topilAI, although the genes are cotranscribed as shown by reverse transcription-PCR. Surprisingly, insertional inactivation ofpilAII 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 thepilAII mutant. However, neither inactivation ofpilAII nor its overexpression affected the amounts of [3H]thymidine-labeled DNA that were competence-specifically bound and taken up by the cells. In thepilAII mutant, the transformation by purified single-stranded DNA (which depends on comA andexbB, 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.

scholarly journals Natural genetic transformation of Pseudomonas stutzeri in a non-sterile soil

Microbiology ◽  
1998 ◽  
Vol 144 (2) ◽  
pp. 569-576 ◽  
Author(s):  
J. Sikorski ◽  
S. Graupner ◽  
M. G. Lorenz ◽  
W. Wackernagel
Keyword(s):  
Genetic Transformation ◽  
Pseudomonas Stutzeri ◽  
Sterile Soil ◽  
Natural Genetic Transformation

scholarly journals Natural Genetic Transformation Generates a Population of Merodiploids in Streptococcus pneumoniae

PLoS Genetics ◽  
2013 ◽  
Vol 9 (9) ◽  
pp. e1003819 ◽  
Author(s):  
Calum Johnston ◽  
Stéphanie Caymaris ◽  
Aldert Zomer ◽  
Hester J. Bootsma ◽  
Marc Prudhomme ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Genetic Transformation ◽  
Natural Genetic Transformation

scholarly journals Natural Genetic Transformation in Monoculture Acinetobacter sp. Strain BD413 Biofilms

2003 ◽  
Vol 69 (3) ◽  
pp. 1721-1727 ◽  
Author(s):  
Larissa Hendrickx ◽  
Martina Hausner ◽  
Stefan Wuertz
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Genetic Transformation ◽  
Exposure Time ◽  
Growth Phase ◽  
Natural Transformation ◽  
Optimal Growth ◽  
Continuous Exposure ◽  
Dna Concentration ◽  
Natural Genetic Transformation

ABSTRACT Horizontal gene transfer by natural genetic transformation in Acinetobacter sp. strain BD413 was investigated by using gfp carried by the autonomously replicating plasmid pGAR1 in a model monoculture biofilm. Biofilm age, DNA concentration, and biofilm mode of growth were evaluated to determine their effects on natural genetic transformation. The highest transfer frequencies were obtained in young and actively growing biofilms when high DNA concentrations were used and when the biofilm developed during continuous exposure to fresh medium without the presence of a significant amount of cells in the suspended fraction. Biofilms were highly amenable to natural transformation. They did not need to advance to an optimal growth phase which ensured the presence of optimally competent biofilm cells. An exposure time of only 15 min was adequate for transformation, and the addition of minute amounts of DNA (2.4 fg of pGAR1 per h) was enough to obtain detectable transfer frequencies. The transformability of biofilms lacking competent cells due to growth in the presence of cells in the bulk phase could be reestablished by starving the noncompetent biofilm prior to DNA exposure. Overall, the evidence suggests that biofilms offer no barrier against effective natural genetic transformation of Acinetobacter sp. strain BD413.

Genetic Competence and Transformation in Oral Streptococci

2001 ◽  
Vol 12 (3) ◽  
pp. 217-243 ◽  
Author(s):  
D.G. Cvitkovitch
Keyword(s):  
Genetic Transformation ◽  
Genetic Information ◽  
Physiological State ◽  
Oral Streptococci ◽  
Dna Uptake ◽  
Genetic Competence ◽  
Gram Positive Bacteria ◽  
Oral Biofilms ◽  
Foreign Dna ◽  
Natural Genetic Transformation

The oral streptococci are normally non-pathogenic residents of the human microflora. There is substantial evidence that these bacteria can, however, act as "genetic reservoirs" and transfer genetic information to transient bacteria as they make their way through the mouth, the principal entry point for a wide variety of bacteria. Examples that are of particular concern include the transfer of antibiotic resistance from oral streptococci to Streptococcus pneumoniae. The mechanisms that are used by oral streptococci to exchange genetic information are not well-understood, although several species are known to enter a physiological state of genetic competence. This state permits them to become capable of natural genetic transformation, facilitating the acquisition of foreign DNA from the external environment. The oral streptococci share many similarities with two closely related Gram-positive bacteria. S. pneumoniae and Bacillus subtilis. In these bacteria, the mechanisms of quorum-sensing, the development of competence, and DNA uptake and integration are well-charaterized. Using this knowledge and the data available in genome databases allowed us to identify putative genes involved in these processes in the oral organism Streptococcus mutans. Models of competence development and genetic transformation in the oral streptococci and strategies to confirm these models are discussed. Future studies of competence in oral biofilms, the natural environment of oral streptococci, will be discussed.

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