title: The vitamin riboflavin and its derivative lumichrome activate the LasR bacterial quorum-sensing receptor.
abstract: Many bacteria use quorum sensing (QS) as an intercellular signaling mechanism to regulate gene expression in local populations. Plant and algal hosts, in turn, secrete compounds that mimic bacterial QS signals, allowing these hosts to manipulate QS-regulated gene expression in bacteria. Lumichrome, a derivative of the vitamin riboflavin, was purified and chemically identified from culture filtrates of the alga Chlamydomonas as a QS signal-mimic compound capable of stimulating the Pseudomonas aeruginosa LasR QS receptor. LasR normally recognizes the N-acyl homoserine lactone (AHL) signal, N-3-oxo-dodecanoyl homoserine lactone. Authentic lumichrome and riboflavin stimulated the LasR receptor in bioassays and lumichrome activated LasR in gel shift experiments. Amino acid substitutions in LasR residues required for AHL binding altered responses to both AHLs and lumichrome or riboflavin. These results and docking studies indicate that the AHL binding pocket of LasR recognizes both AHLs and the structurally dissimilar lumichrome or riboflavin. Bacteria, plants, and algae commonly secrete riboflavin or lumichrome, raising the possibility that these compounds could serve as either QS signals or as interkingdom signal mimics capable of manipulating QS in bacteria with a LasR-like receptor.
authors.affiliation: Department of Plant Sciences, University of California, Davis, CA 95616, USA.
authors.forename: Sathish
authors.initials: S
authors.lastname: Rajamani
authors.forename: Wolfgang D
authors.initials: WD
authors.lastname: Bauer
authors.forename: Jayne B
authors.initials: JB
authors.lastname: Robinson
authors.forename: John M
authors.initials: JM
authors.lastname: Farrow
authors.forename: Everett C
authors.initials: EC
authors.lastname: Pesci
authors.forename: Max
authors.initials: M
authors.lastname: Teplitski
authors.forename: Mengsheng
authors.initials: M
authors.lastname: Gao
authors.forename: Richard T
authors.initials: RT
authors.lastname: Sayre
authors.forename: Donald A
authors.initials: DA
authors.lastname: Phillips
mesh_terms: D054742:Acyl-Butyrolactones / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism / Q000502:physiology*; D001665:Binding Sites; D002696:Chlamydomonas / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005415:Flavins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D053038:Quorum Sensing / Q000187:drug effects* / Q000502:physiology; D012256:Riboflavin / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D015534:Trans-Activators / Q000378:metabolism / Q000502:physiology*; D014803:Vitamin B Complex / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology
chemical_list: D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; D005415:Flavins; C080365:LasR protein, Pseudomonas aeruginosa; D015534:Trans-Activators; C001559:7,8-dimethylalloxazine; D014803:Vitamin B Complex; D012256:Riboflavin