Journal of Bacteriology, September 2000, p. 4696-4703, Vol. 182, No. 17
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Hoffmann-La Roche Ltd., CH-4070 Basel, Switzerland,1 and Infection and Immunity, University of Glasgow, Glasgow G12 8QQ, Scotland2
Received 15 March 2000/Accepted 1 June 2000
We have identified in the Streptococcus pneumoniae
genome sequence a two-component system (TCS13, Blp [bacteriocin-like
peptide]) which is closely related to quorum-sensing systems
regulating cell density-dependent phenotypes such as the development of
genetic competence or the production of antimicrobial peptides in
lactic acid bacteria. In this study we present evidence that TCS13 is a
peptide-sensing system that controls a regulon including genes encoding
Blps. Downstream of the Blp TCS (BlpH R) we identified open reading
frames (blpAB) that have the potential to encode an ABC
transporter that is homologous to the ComA/B export system for the
competence-stimulating peptide ComC. The putative translation product
of blpC, a small gene located downstream of
blpAB, has a leader peptide with a Gly-Gly motif. This
leader peptide is typical of precursors processed by this family of
transporters. Microarray-based expression profiling showed that a
synthetic oligopeptide corresponding to the processed form of BlpC
(BlpC*) induces a distinct set of 16 genes. The changes in the
expression profile elicited by synthetic BlpC* depend on BlpH since
insertional inactivation of its corresponding gene abolishes
differential gene induction. Comparison of the promoter regions of the
blp genes disclosed a conserved sequence element formed by
two imperfect direct repeats upstream of extended
10 promoter
elements. We propose that BlpH is the sensor for BlpC* and the
conserved sequence element is a recognition sequence for the BlpR
response regulator.
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