Lsr-mediated transport and processing of AI-2 in Salmonella typhimurium. Author Michiko Taga, Stephen Miller, Bonnie Bassler Publication Year 2003 Type Journal Article Abstract The LuxS-dependent autoinducer AI-2 is proposed to function in interspecies cell-cell communication in bacteria. In Salmonella typhimurium, AI-2 is produced and released during exponential growth and is subsequently imported into the bacteria via the Lsr (luxS regulated) ATP binding cassette (ABC) transporter. AI-2 induces transcription of the lsrACDBFGE operon, the first four genes of which encode the Lsr transport apparatus. In this report, we identify and characterize LsrK, a new protein that is required for the regulation of the lsr operon and the AI-2 uptake process. LsrK is a kinase that phosphorylates AI-2 upon entry into the cell. Our data indicate that phosphorylation of AI-2 results in its sequestration in the cytoplasm. We suggest that phospho-AI-2 is the inducer responsible for inactivation of LsrR, the repressor of the lsr operon. We also show that two previously uncharacterized members of the lsr operon, LsrF and LsrG, are necessary for the further processing of phospho-AI-2. Transport and processing of AI-2 could be required for removing the quorum-sensing signal, conveying the signal to an internal detector and/or scavenging boron. Keywords Gene Expression Regulation, Bacterial, Biological Transport, Bacterial Proteins, Protein Kinases, Lactones, Phosphorylation, Homoserine, Salmonella typhimurium, ATP-Binding Cassette Transporters, Epistasis, Genetic, Operon, Phenotype Journal Mol Microbiol Volume 50 Issue 4 Pages 1411-27 Date Published 2003 Nov ISSN Number 0950-382X DOI 10.1046/j.1365-2958.2003.03781.x Alternate Journal Mol Microbiol PMID 14622426 PubMedGoogle ScholarBibTeXEndNote X3 XML