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J Bacteriol

Title:		Bacteriocin activity of Streptococcus pneumoniae is controlled by the serine protease HtrA via posttranscriptional regulation
Author(s):		Dawid S; Sebert ME; Weiser JN;
Address:		"Department of Pediatrics, The Children's Hospital of Philadelphia, Pennsylvania, USA. sdawid@umich.edu"
Journal Title:		J Bacteriol
Year:		2009
Volume:		20081219
Issue:		5
Page Number:		1509 - 1518
DOI:		10.1128/JB.01213-08
ISSN/ISBN:		1098-5530 (Electronic) 0021-9193 (Print) 0021-9193 (Linking)
Abstract:		"The blp locus of a type 6A strain of Streptococcus pneumoniae encodes a two-peptide bacteriocin, pneumocin MN, which mediates intraspecies competition during mouse nasopharyngeal colonization. This locus is regulated by a quorum-sensing mechanism consisting of a dedicated two-component regulatory system and a peptide pheromone. Like most clinical isolates, this type 6A strain can be separated into opaque and transparent colony variants, each playing a different role during pneumococcal infection. In this study, we show that the blp locus is differentially regulated at the posttranscriptional level in pneumococcal opacity variants. Transparent and opaque variants produce equivalent amounts of blpMNPO transcript when stimulated with a synthetic pheromone, but transparent variants have no pneumocin MN-mediated inhibitory activity while opaque variants produce large zones of inhibitory activity. The differential regulation in opacity variants is driven by the two-component regulatory system CiaRH via its regulation of the serine protease HtrA. Transparent mutants deficient in CiaH or HtrA show increased pneumocin MN-mediated inhibition. In addition, these mutants demonstrate alterations in their dose response to a synthetic peptide pheromone, suggesting that HtrA activity impacts pneumocin MN production at the level of signaling. This, in addition to its known effects on competence, suggests that HtrA is a pleiotropic regulator whose protease activity affects several important bacterial pathways. The complex regulation of pneumocins may allow the pneumococcus to reserve the secretion of active peptides for situations where the benefit of their inhibitory activity outweighs the cost of their production"
Keywords:		"Amino Acid Sequence Bacterial Proteins/genetics/metabolism Bacteriocins/*biosynthesis/chemistry Culture Media *Gene Expression Regulation, Bacterial Heat-Shock Proteins/chemistry/genetics/*metabolism Humans Molecular Sequence Data Peptides/chemical synthe;"
Notes:		"MedlineDawid, Suzanne Sebert, Michael E Weiser, Jeffrey N eng R01 AI044231/AI/NIAID NIH HHS/ AI052129/AI/NIAID NIH HHS/ K08 AI071090/AI/NIAID NIH HHS/ R21 AI044231/AI/NIAID NIH HHS/ AI44231/AI/NIAID NIH HHS/ K08 AI052129/AI/NIAID NIH HHS/ AI071090/AI/NIAID NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't 2008/12/24 J Bacteriol. 2009 Mar; 191(5):1509-18. doi: 10.1128/JB.01213-08. Epub 2008 Dec 19"