Differential gene expression shows natural brominated furanones interfere with the autoinducer-2 bacterial signaling system of Escherichia coli

Biotechnol Bioeng. 2004 Dec 5;88(5):630-42. doi: 10.1002/bit.20259.

Abstract

The quorum sensing disrupter (5Z)-4-bromo-5-(bromomethylene)-3-butyl-2(5H)-furanone (furanone) of the alga Delisea pulchra was previously found by us (Environ Microbiol 3:731-736, 2001) to inhibit quorum sensing in Escherichia coli via autoinducer-2 (AI-2, produced by LuxS). In this study, DNA microarrays were used to study the genetic basis of this natural furanone inhibition of AI-2 signaling (significant values with p < 0.05 are reported). Using DNA microarrays, the AI-2 mutant Escherichia coli DH5alpha was compared with the AI-2 wild-type strain, E. coli K12, to determine how AI-2 influenced gene expression. Escherichia coli K12 was also grown with 0 and 60 microg/mL furanone to study the inhibition of quorum sensing gene expression. It was found that 166 genes were differentially expressed by AI-2 (67 were induced and 99 were repressed) and 90 genes were differentially expressed by furanone (34 were induced and 56 were repressed). Importantly, 79% (44 out of 56) of the genes repressed by furanone were induced by AI-2, which indicated that furanone inhibited AI-2 signaling and influenced the same suite of genes as a regulon. Most of these genes have functions of chemotaxis, motility, and flagellar synthesis. Interestingly, the aerotaxis genes aer and tsr were discovered to be induced by AI-2 and repressed by furanone. Representative microarray results were confirmed by RNA dot blotting. Furthermore, the E. coli air-liquid interface biofilm formation was repressed by furanone, supporting the results that taxis and flagellar genes were repressed by furanone. The autoinducer bioassay indicated that 100 microg/mL furanone decreased the extracellular concentration of AI-2 2-fold, yet luxS and pfs transcription were not significantly altered. Hence, furanone appeared to alter AI-2 signaling post-transcriptionally.

MeSH terms

  • Chemotaxis / drug effects
  • Chemotaxis / physiology
  • Dose-Response Relationship, Drug
  • Escherichia coli / drug effects
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / metabolism*
  • Furans / pharmacokinetics*
  • Gene Expression Profiling / methods
  • Gene Expression Regulation, Bacterial / drug effects
  • Gene Expression Regulation, Bacterial / physiology*
  • Homoserine / analogs & derivatives*
  • Homoserine / genetics
  • Homoserine / metabolism*
  • Lactones / metabolism*
  • Signal Transduction / drug effects*

Substances

  • Escherichia coli Proteins
  • Furans
  • Lactones
  • N-octanoylhomoserine lactone
  • Homoserine