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 A programmed cell division delay preserves genome integrity during natural genetic transformation in Streptococcus pneumoniae

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Matthieu J. Bergé ◽  
Chryslène Mercy ◽  
Isabelle Mortier-Barrière ◽  
Michael S. VanNieuwenhze ◽  
Yves V. Brun ◽  
...  
Keyword(s):  
Cell Division ◽  
Streptococcus Pneumoniae ◽  
Genetic Transformation ◽  
Genome Integrity ◽  
Natural Genetic Transformation

scholarly journals An Unstable Competence-Induced Protein, CoiA, Promotes Processing of Donor DNA after Uptake during Genetic Transformation in Streptococcus pneumoniae

2006 ◽  
Vol 188 (14) ◽  
pp. 5177-5186 ◽  
Author(s):  
Bhushan V. Desai ◽  
Donald A. Morrison
Keyword(s):  
Streptococcus Pneumoniae ◽  
Genetic Transformation ◽  
Transcriptional Activation ◽  
Response Regulator ◽  
Specific Response ◽  
Dna Uptake ◽  
Gram Positive Bacteria ◽  
Specific Alternative ◽  
Natural Genetic Transformation

ABSTRACT Natural genetic transformation in Streptococcus pneumoniae entails transcriptional activation of at least two sets of genes. One set of genes, activated by the competence-specific response regulator ComE, is involved in initiating competence, whereas a second set is activated by the competence-specific alternative sigma factor ComX and functions in DNA uptake and recombination. Here we report an initial characterization of CoiA, a ComX-dependent gene product that is induced during competence and is required for transformation. CoiA is widely conserved among gram-positive bacteria, and in streptococci, the entire coiA locus composed of four genes is conserved. By use of immunoblot assay, we show that, similar to its message, CoiA protein is transient, appearing at 10 min and largely disappearing by 30 min post-competence induction. Using complementation analysis, we establish that coiA is the only gene of this induced locus needed for transformability. We find no indication of CoiA having a role in regulating competence. Finally, using 32P- and 3H-labeled donor DNA, we demonstrate that a coiA mutant can internalize normal amounts of donor DNA compared to the wild-type strain but is unable to process it into viable transformants, suggesting a role for CoiA after DNA uptake, either in DNA processing or recombination.

scholarly journals Choline-Binding Protein D (CbpD) in Streptococcus pneumoniae Is Essential for Competence-Induced Cell Lysis

2005 ◽  
Vol 187 (13) ◽  
pp. 4338-4345 ◽  
Author(s):  
Louise Kausmally ◽  
Ola Johnsborg ◽  
Merete Lunde ◽  
Eivind Knutsen ◽  
Leiv Sigve Håvarstein
Keyword(s):  
Streptococcus Pneumoniae ◽  
Genetic Transformation ◽  
Binding Protein ◽  
Bacterial Species ◽  
Ectopic Expression ◽  
Cell Lysis ◽  
Extracellular Dna ◽  
Naked Dna ◽  
Dna Release ◽  
Natural Genetic Transformation

ABSTRACT Streptococcus pneumoniae is an important human pathogen that is able to take up naked DNA from the environment by a quorum-sensing-regulated process called natural genetic transformation. This property enables members of this bacterial species to efficiently acquire new properties that may increase their ability to survive and multiply in the human host. We have previously reported that induction of the competent state in a liquid culture of Streptococcus pneumoniae triggers lysis of a subfraction of the bacterial population resulting in release of DNA. We have also proposed that such competence-induced DNA release is an integral part of natural genetic transformation that has evolved to increase the efficiency of gene transfer between pneumococci. In the present work, we have further elucidated the mechanism behind competence-induced cell lysis by identifying a putative murein hydrolase, choline-binding protein D (CbpD), as a key component of this process. By using real-time PCR to estimate the amount of extracellular DNA in competent relative to noncompetent cultures, we were able to show that competence-induced cell lysis and DNA release are strongly attenuated in a cbpD mutant. Ectopic expression of CbpD in the presence or absence of other competence proteins revealed that CbpD is essentially unable to cause cell lysis on its own but depends on at least one additional protein expressed during competence.

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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