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Proc Natl Acad Sci U S A

Title:		Induction of natural competence in Streptococcus pneumoniae triggers lysis and DNA release from a subfraction of the cell population
Author(s):		Steinmoen H; Knutsen E; Havarstein LS;
Address:		"Department of Chemistry and Biotechnology, Agricultural University of Norway, P.O. Box 5040, N-1432 As, Norway"
Journal Title:		Proc Natl Acad Sci U S A
Year:		2002
Volume:		99
Issue:		11
Page Number:		7681 - 7686
DOI:		10.1073/pnas.112464599
ISSN/ISBN:		0027-8424 (Print) 1091-6490 (Electronic) 0027-8424 (Linking)
Abstract:		"Naturally competent bacteria have the ability to take up free DNA from the surrounding medium and incorporate this DNA into their genomes by homologous recombination. In naturally competent Streptococcus pneumoniae, and related streptococcal species from the mitis phylogenetic group, the competent state is not a constitutive property but is induced by a peptide pheromone through a quorum-sensing mechanism. Recent studies have shown that natural genetic transformation is an important mechanism for gene exchange between streptococci in nature. A prerequisite for effective gene exchange is the presence of streptococcal donor DNA in the environment. Despite decades of study of the transformation process we still do not know how this donor DNA is released from streptococcal cells to the external milieu. Traditionally, it has been assumed that donor DNA originates from cells that die and fall apart from natural causes. In this study we show that induction of the competent state initiates release of DNA from a subfraction of the bacterial population, probably by cell lysis. The majority of the cells induced to competence take up DNA and act as recipients, whereas the rest release DNA and act as donors. These findings show that natural transformation in streptococci provides a natural mechanism for genetic recombination that resembles sex in higher organisms"
Keywords:		"Amino Acid Sequence DNA Primers DNA, Bacterial/*metabolism Kinetics Molecular Sequence Data Mutagenesis Peptide Fragments/chemistry Polymerase Chain Reaction Streptococcus pneumoniae/enzymology/*genetics/physiology *Transformation, Bacterial/genetics beta;"
Notes:		"MedlineSteinmoen, Hilde Knutsen, Eivind Havarstein, Leiv Sigve eng Research Support, Non-U.S. Gov't 2002/05/29 Proc Natl Acad Sci U S A. 2002 May 28; 99(11):7681-6. doi: 10.1073/pnas.112464599"