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J Bacteriol

Title:		Natural competence in the genus Streptococcus: evidence that streptococci can change pherotype by interspecies recombinational exchanges
Author(s):		Havarstein LS; Hakenbeck R; Gaustad P;
Address:		"Department of Biotechnological Sciences, Agricultural University of Norway, As. sigve.havarstein@ibf.nlh.no"
Journal Title:		J Bacteriol
Year:		1997
Volume:		179
Issue:		21
Page Number:		6589 - 6594
DOI:		10.1128/jb.179.21.6589-6594.1997
ISSN/ISBN:		0021-9193 (Print) 1098-5530 (Electronic) 0021-9193 (Linking)
Abstract:		"To map the incidence of natural competence in the genus Streptococcus, we used PCR to screen a number of streptococcal strains for the presence of the recently identified competence regulation operon, containing the comC, -D, and -E genes. This approach established that the operon is present in strains belonging to the S. mitis and S. anginosus groups, but it was not detected in the other strains examined. Competence is induced in S. pneumoniae and S. gordonii by strain-specific peptide pheromones, competence-stimulating peptides (CSPs). With its unique primary structure, each CSP represents a separate pheromone type (pherotype), which is recognized by the signalling domain of the downstream histidine kinase, ComD. Thus, all bacteria induced to competence by a particular CSP belong to the same pherotype. In this study, we identified a number of new pherotypes by sequencing the genes encoding the CSP and its receptor from different streptococcal species. We found that in several cases, these genes have a mosaic structure which must have arisen as the result of recombination between two distinct allelic variants. The observed mosaic blocks encompass the region encoding the CSP and the CSP-binding domain of the histidine kinase. Consequently, the recombination events have led to switches in pherotype for the strains involved. This suggests a novel mechanism for the adaptation of naturally competent streptococci to new environmental conditions"
Keywords:		"Amino Acid Sequence Bacterial Proteins/*genetics DNA, Bacterial/metabolism Genetic Variation Histidine Kinase Molecular Sequence Data *Multienzyme Complexes Operon Peptides/*genetics Pheromones/*genetics Polymerase Chain Reaction Protein Kinases Sequence;"
Notes:		"MedlineHavarstein, L S Hakenbeck, R Gaustad, P eng Comparative Study 1997/11/14 J Bacteriol. 1997 Nov; 179(21):6589-94. doi: 10.1128/jb.179.21.6589-6594.1997"