scholarly journals Positive Selection in the ComC-ComD System of Streptococcal Species

2006 ◽  
Vol 188 (17) ◽  
pp. 6429-6434 ◽  
Author(s):  
Hisako Ichihara ◽  
Kei-ichi Kuma ◽  
Hiroyuki Toh
Keyword(s):  
Genetic Transformation ◽  
Positive Selection ◽  
Bacterial Populations ◽  
First Report ◽  
Streptococcal Species ◽  
Natural Genetic Transformation

ABSTRACT Competence-stimulating peptide (CSP) and ComD of the streptococcal species are a pheromone and its receptor, respectively, involved in the regulation of competence for natural genetic transformation. We show here that these molecules have undergone positive selection. This study is the first report of positive selection due to competition among bacterial populations.

scholarly journals Properties and Biological Role of Streptococcal Fratricins

2012 ◽  
Vol 78 (10) ◽  
pp. 3515-3522 ◽  
Author(s):  
Kari Helene Berg ◽  
Truls Johan Biørnstad ◽  
Ola Johnsborg ◽  
Leiv Sigve Håvarstein
Keyword(s):  
Cell Wall ◽  
Genetic Transformation ◽  
Natural Transformation ◽  
Current View ◽  
Dna Uptake ◽  
Cell Wall Degrading Enzymes ◽  
Content Type ◽  
Streptococcal Species ◽  
Natural Genetic Transformation

ABSTRACTCompetence for natural genetic transformation is widespread in the genusStreptococcus. The current view is that all streptococcal species possess this property. In addition to the proteins required for DNA uptake and recombination, competent streptococci secrete muralytic enzymes termed fratricins. Since the synthesis and secretion of these cell wall-degrading enzymes are always coupled to competence development in streptococci, fratricins are believed to carry out an important function associated with natural transformation. This minireview summarizes what is known about the properties of fratricins and discusses their possible biological roles in streptococcal transformation.

scholarly journals Steady at the wheel: conservative sex and the benefits of bacterial transformation

2016 ◽  
Author(s):  
Ole Herman Ambur ◽  
Jan Engelstädter ◽  
Pål J. Johnsen ◽  
Eric L. Miller ◽  
Daniel E. Rozen
Keyword(s):  
Genetic Transformation ◽  
Large Body ◽  
Theoretical Studies ◽  
Bacterial Cells ◽  
Bacterial Transformation ◽  
Bacterial Populations ◽  
Direct Benefits ◽  
Foreign Dna ◽  
Genomic Conservation ◽  
Natural Genetic Transformation

SummaryMany bacteria are highly sexual, but the reasons for their promiscuity remain obscure. Did bacterial sex evolve to maximize diversity and facilitate adaptation in a changing world, or does it instead help to retain the bacterial functions that work right now? In other words, is bacterial sex innovative or conservative? Our aim in this review is to integrate experimental, bioinformatic and theoretical studies to critically evaluate these alternatives, with a main focus on natural genetic transformation, the bacterial equivalent of eukaryotic sexual reproduction. First, we provide a general overview of several hypotheses that have been put forward to explain the evolution of transformation. Next, we synthesize a large body of evidence highlighting the numerous passive and active barriers to transformation that have evolved to protect bacteria from foreign DNA, thereby increasing the likelihood that transformation takes place among clonemates. Our critical review of the existing literature provides support for the view that bacterial transformation is maintained as a means of genomic conservation that provides direct benefits to both individual bacterial cells and to transformable bacterial populations. We examine the generality of this view across bacteria and contrast this explanation with the different evolutionary roles proposed to maintain sex in eukaryotes.

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.

Natural genetic transformation: prevalence, mechanisms and function

2007 ◽  
Vol 158 (10) ◽  
pp. 767-778 ◽  
Author(s):  
Ola Johnsborg ◽  
Vegard Eldholm ◽  
Leiv Sigve Håvarstein
Keyword(s):  
Genetic Transformation ◽  
And Function ◽  
Natural Genetic Transformation

scholarly journals Genetic transformation of the dinoflagellate chloroplast

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Isabel C Nimmo ◽  
Adrian C Barbrook ◽  
Imen Lassadi ◽  
Jit Ern Chen ◽  
Katrin Geisler ◽  
...  
Keyword(s):  
Coral Reefs ◽  
Genetic Transformation ◽  
Chloroplast Genome ◽  
Genetically Modified ◽  
Genetic Material ◽  
Chloroplast Transformation ◽  
Marine Environments ◽  
First Report ◽  
The Relationship ◽  
Reef Ecosystem

Coral reefs are some of the most important and ecologically diverse marine environments. At the base of the reef ecosystem are dinoflagellate algae, which live symbiotically within coral cells. Efforts to understand the relationship between alga and coral have been greatly hampered by the lack of an appropriate dinoflagellate genetic transformation technology. By making use of the plasmid-like fragmented chloroplast genome, we have introduced novel genetic material into the dinoflagellate chloroplast genome. We have shown that the introduced genes are expressed and confer the expected phenotypes. Genetically modified cultures have been grown for 1 year with subculturing, maintaining the introduced genes and phenotypes. This indicates that cells continue to divide after transformation and that the transformation is stable. This is the first report of stable chloroplast transformation in dinoflagellate algae.

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