The LuxS-dependent autoinducer Al-2 controls the expression of an ABC transporter that functions in Al-2 uptake in Salmonella typhimurium

Citation
Me. Taga et al., The LuxS-dependent autoinducer Al-2 controls the expression of an ABC transporter that functions in Al-2 uptake in Salmonella typhimurium, MOL MICROB, 42(3), 2001, pp. 777-793
Citations number
53
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950-382X → ACNP
Volume
42
Issue
3
Year of publication
2001
Pages
777 - 793
Database
ISI
SICI code
0950-382X(200111)42:3<777:TLAACT>2.0.ZU;2-I
Abstract
In a process called quorum sensing, bacteria communicate with one another u sing secreted chemical signalling molecules termed autoinducers. A novel au toinducer called Al-2, originally discovered in the quorum-sensing bacteriu m Vibrio harveyi, is made by many species of Gram-negative and Grampositive bacteria. In every case, production of Al-2 is dependent on the LuxS autoi nducer synthase. The genes regulated by Al-2 in most of these luxS-containi ng species of bacteria are not known. Here, we describe the identification and characterization of Al-2-regulated genes in Salmonella typhimurium. We find that LuxS and Al-2 regulate the expression of a previously unidentifie d operon encoding an ATP binding cassette (ABC)-type transporter. We have n amed this operon the Isr (luxS regulated) operon. The Lsr transporter has h omology to the ribose transporter of Esctoerichia coli and S. typhimurium. A gene encoding a DNA-binding protein that is located adjacent to the Lsr t ransporter structural operon is required to link Al-2 detection to operon e xpression. This gene, which we have named IsrR, encodes a protein that repr esses Isr operon expression in the absence of Al-2. Mutations in the Isr op eron render S. typhimurium unable to eliminate Al-2 from the extracellular environment, suggesting that the role of the Lsr apparatus is to transport Al-2 into the cells. It is intriguing that an operon regulated by Al-2 enco des functions resembling the ribose transporter, given recent findings that Al-2 is derived from the ribosyl moiety of S-ribosylhomocysteine.