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J Bacteriol

Title:		Competence without a competence pheromone in a natural isolate of Streptococcus infantis
Author(s):		Ween O; Teigen S; Gaustad P; Kilian M; Havarstein LS;
Address:		"Department of Chemistry and Biotechnology, Agricultural University of Norway, N-1432 As, Norway"
Journal Title:		J Bacteriol
Year:		2002
Volume:		184
Issue:		13
Page Number:		3426 - 3432
DOI:		10.1128/JB.184.13.3426-3432.2002
ISSN/ISBN:		0021-9193 (Print) 1098-5530 (Electronic) 0021-9193 (Linking)
Abstract:		"Many streptococcal species belonging to the mitis and anginosus phylogenetic groups are known to be naturally competent for genetic transformation. Induction of the competent state in these bacteria is regulated by a quorum-sensing mechanism consisting of a secreted peptide pheromone encoded by comC and a two-component regulatory system encoded by comDE. Here we report that a natural isolate of a mitis group streptococcus (Atu-4) is competent for genetic transformation even though it has lost the gene encoding the competence pheromone. In contrast to other strains, induction of competence in Atu-4 is not regulated by cell density, since highly diluted cultures of this strain are still competent. Interestingly, competence in the Atu-4 strain is lost if the gene encoding the response regulator ComE is disrupted, demonstrating that this component of the quorum-sensing apparatus is still needed for competence development. These results indicate that mutations in ComD or ComE have resulted in a gain-of-function phenotype that allows competence without a competence pheromone. A highly similar strain lacking comC was isolated independently from another individual, suggesting that strains with this phenotype are able to survive in nature in competition with wild-type strains"
Keywords:		"Amino Acid Sequence Bacterial Proteins/*genetics Histidine Kinase Molecular Sequence Data *Multienzyme Complexes Protein Kinases/genetics Streptococcus/*physiology *Transformation, Bacterial;"
Notes:		"MedlineWeen, Ola Teigen, Svanhild Gaustad, Peter Kilian, Mogens Havarstein, Leiv Sigve eng Research Support, Non-U.S. Gov't 2002/06/12 J Bacteriol. 2002 Jul; 184(13):3426-32. doi: 10.1128/JB.184.13.3426-3432.2002"