title: Transcriptional and metabolomic consequences of LuxS inactivation reveal a metabolic rather than quorum-sensing role for LuxS in Lactobacillus reuteri 100-23.
abstract: Autoinducer-2 (AI-2)-mediated quorum sensing has been extensively studied in relation to the regulation of microbial behavior. There are, however, two potential roles for the AI-2 synthase (LuxS). The first is in the production of AI-2 and the second is as an enzyme in the activated methyl cycle, where it catalyzes the conversion of S-ribosylhomocysteine to homocysteine. The by-product of the reaction catalyzed by LuxS is (S)-4,5-dihydroxy-2,3-pentanedione, which spontaneously forms the furanones known collectively as AI-2. The mammalian gut contains a complex collection of bacterial species so a method of interspecies communication might influence community structure and function. Lactobacillus reuteri 100-23 is an autochthonous inhabitant of the rodent forestomach, where it adheres to the nonsecretory epithelium, forming a biofilm. Microarray comparisons of gene expression profiles of the L. reuteri 100-23 wild type and a luxS mutant under different culture conditions revealed altered transcription of genes encoding proteins associated with cysteine biosynthesis/oxidative stress response, urease activity, and sortase-dependent proteins. Metabolomic analysis showed that the luxS mutation affected cellular levels of fermentation products, fatty acids and amino acids. Cell density-dependent changes (log phase versus stationary phase growth) in gene transcription were not detected, indicating that AI-2 was unlikely to be involved in gene regulation mediated by quorum sensing in L. reuteri 100-23.
authors.affiliation: Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.
authors.forename: Charlotte M
authors.initials: CM
authors.lastname: Wilson
authors.forename: Raphael B M
authors.initials: RB
authors.lastname: Aggio
authors.forename: Paul W
authors.initials: PW
authors.lastname: O'Toole
authors.forename: Silas
authors.initials: S
authors.lastname: Villas-Boas
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Tannock
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D013437:Carbon-Sulfur Lyases / Q000235:genetics* / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D020868:Gene Silencing; D006714:Homoserine / Q000031:analogs & derivatives / Q000378:metabolism; D052200:Limosilactobacillus reuteri / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D007783:Lactones / Q000378:metabolism; D055432:Metabolomics; D009154:Mutation; D053038:Quorum Sensing; D014158:Transcription, Genetic
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D005227:Fatty Acids; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D006714:Homoserine; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria