The Bacillus subtilis recH342 strain, which decreases interspecies recombination without significantly affecting the frequency of transformation with homogamic DNA, carried a point mutation in the putative recX (yfhG) gene, and the mutation was renamed as recX342. We show that RecX (264 residues long), which shares partial identity with the Proteobacterial RecX (<180 residues), is a genuine rec...

Natural genetic transformation in Streptococcus pneumoniae is controlled by a quorum-sensing system, which acts through the competence-stimulating peptide (CSP) for transient activation of genes required for competence. More than 100 genes have been identified as CSP regulated by use of DNA microarray analysis. One of the CSP-induced genes required for genetic competence is comW. As the express...

Natural transformation is assumed to be the most likely mechanism by which DNA from transgenic plants could be horizontally transferred to bacteria. In order to determine the occurrence of naturally transformable bacteria amongst bulk and rhizosphere soil bacteria, different transformation strategies were employed using either plasmid DNA (IncQ plasmids pSM1890 and pSM1885, conferring GFP, Sm(r...

Natural transformation is assumed to be the most likely mechanism by which DNA from transgenic plants could be horizontally transferred to bacteria. In order to determine the occurrence of naturally transformable bacteria amongst bulk and rhizosphere soil bacteria, different transformation strategies were employed using either plasmid DNA (IncQ plasmids pSM1890 and pSM1885, conferring GFP, Smr,...

A phylogenetically diverse subset of bacterial species are naturally competent for transformation by DNA. Transformation entails recombination of genes between different lineages, representing a form of bacterial sex that increases standing genetic variation. We first assess whether homologous recombination by transformation is favored by evolution. Using stochastic population genetic computer ...

Recent evidence has indicated that natural genetic transformation occurs in Vibrio cholerae, and that it requires both induction by chitin oligosaccharides, like chitohexaose, and expression of a putative regulatory gene designated tfoX. Using sequence and phylogenetic analyses we have found two tfoX paralogues in all sequenced genomes of the genus Vibrio. Like V. cholerae, when grown in chitoh...

The extreme thermophile Thermus thermophilus HB27 exhibits high frequencies of natural transformation. Although we recently reported identification of the first competence genes in Thermus, the molecular basis of DNA uptake is unknown. A pilus-like structure is assumed to be involved. Twelve genes encoding prepilin-like proteins were identified in three loci in the genome of T. thermophilus. Mu...

DNA has recently been described as a major structural component of the extracellular matrix in biofilms. In streptococci, the competence-stimulating peptide (CSP) cell-to-cell signal is involved in competence for genetic transformation, biofilm formation, and autolysis. Among the genes regulated in response to the CSP are those involved in binding and uptake of extracellular DNA. We show in thi...

It has been reported (Nava, Galis, and Beiser, Nature 197:903, 1963) that immunization of rabbits with competent pneumococci stimulates the production of antibodies which inhibit transformation. Similar data reported below show that the antigenic structure of transformable streptococci in the competent state differs from the antigenic structure of cells in the noncompetent state. Competence in ...