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Title: Functional analysis of the quorum-sensing streptococcal invasion locus ( sil)
Authors: Belotserkovsky L.
Baruch M.
Peer A.
Dov E.
Ravins M.
Mishalian I.
Persky M.
Smith Y.
Hanski E. 
Keywords: bacterial protein
SilCR peptide
unclassified drug
bacterial colonization
bacterial strain
deletion mutant
gene activation
gene expression
gene identification
gene locus
group G streptococcus
host pathogen interaction
nucleotide sequence
promoter region
quorum sensing
RNA analysis
sequence analysis
signal transduction
site directed mutagenesis
streptococcal invasion locus
Streptococcus group A
Bacteria (microorganisms)
Streptococcus sp. 'group A'
Streptococcus sp. 'group G'
Issue Date: 2009
Citation: Belotserkovsky L., Baruch M., Peer A., Dov E., Ravins M., Mishalian I., Persky M., Smith Y., Hanski E. (2009). Functional analysis of the quorum-sensing streptococcal invasion locus ( sil). PLoS Pathogens 5 (11) : e1000651. ScholarBank@NUS Repository.
Rights: Attribution 4.0 International
Abstract: Group A streptococcus (GAS) causes a wide variety of human diseases, and at the same time, GAS can also circulate without producing symptoms, similar to its close commensal relative, group G streptococcus (GGS). We previously identified, by transposon-tagged mutagenesis, the streptococcal invasion locus (sil). sil is a quorum-sensing regulated locus which is activated by the autoinducer peptide SilCR through the two-component system SilA-SilB. Here we characterize the DNA promoter region necessary for SilA-mediated activation. This site is composed of two direct repeats of 10 bp, separated by a spacer of 11 bp. Fusion of this site to gfp allowed us to systematically introduce single-base substitutions in the repeats region and to assess the relative contribution of various positions to promoter strength. We then developed an algorithm giving different weights to these positions, and performed a chromosome-wide bioinformatics search which was validated by transcriptome analysis. We identified 13 genes, mostly bacteriocin related, that are directly under the control of SilA. Having developed the ability to quantify SilCR signaling via GFP accumulation prompted us to search for GAS and GGS strains that sense and produce SilCR. While the majority of GAS strains lost sil, all GGS strains examined still possess the locus and ?63% are able to respond to exogenously added SilCR. By triggering the autoinduction circle using a minute concentration of synthetic SilCR, we identified GAS and GGS strains that are capable of sensing and naturally producing SilCR, and showed that SilCR can be sensed across these streptococci species. These findings suggest that sil may be involved in colonization and establishment of commensal host-bacterial relationships. © 2009 Belotserkovsky et al.
Source Title: PLoS Pathogens
ISSN: 15537366
DOI: 10.1371/journal.ppat.1000651
Rights: Attribution 4.0 International
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