Let LuxS speak up in AI-2 signaling》.pdfVIP

Opinion TRENDS in Microbiology Vol.14 No.3 March 2006 Let LuxS speak up in AI-2 signaling Sigrid C.J. De Keersmaecker, Kathleen Sonck and Jos Vanderleyden Centre of Microbial and Plant Genetics, K.U. Leuven, Kasteelpark Arenberg 20, 3001 Leuven, Belgium Quorum sensing is a process of bacterial cell–cell metabolic function in the activated methyl cycle, namely communication that uses small diffusible molecules to the recycling of S-adenosylhomocysteine (SAH) to homo- coordinate diverse behaviors in response to population cysteine, although an alternative pathway does exist density. The only quorum-sensing system shared by (Figure 1). This could also explain why LuxS is conserved Gram-positive and Gram-negative bacteria involves the among w50% of the sequenced bacteria [7,10,11]. production of autoinducer-2 (AI-2). The AI-2 synthase In a recent review, Vendeville et al. [5] clearly LuxS is widely distributed among the Bacteria, which documented the two potential roles of LuxS and AI-2 in suggests that AI-2 is a language for interspecies metabolism and quorum sensing. In our opinion, the communication. However, LuxS is also an integral current knowledge about the regulation of luxS and LuxS component of the activated methyl cycle in bacteria. activity is insufficient to assign a signaling role to AI-2 in LuxS-based quorum sensing has been intensively all of the bacteria in which AI-2 has been detected so far. studied in the past decade, mostly in relation to the AI- Furthermore, we suggest approaches for future exper- 2 molecule and the downstream effects of luxS knock- iments that take into account the possible