title: FabR regulates Salmonella biofilm formation via its direct target FabB.
abstract: BACKGROUND
  Biofilm formation is an important survival strategy of Salmonella in all environments. By mutant screening, we showed a knock-out mutant of fabR, encoding a repressor of unsaturated fatty acid biosynthesis (UFA), to have impaired biofilm formation. In order to unravel how this regulator impinges on Salmonella biofilm formation, we aimed at elucidating the S. Typhimurium FabR regulon. Hereto, we applied a combinatorial high-throughput approach, combining ChIP-chip with transcriptomics.
  
  
  RESULTS
  All the previously identified E. coli FabR transcriptional target genes (fabA, fabB and yqfA) were shown to be direct S. Typhimurium FabR targets as well. As we found a fabB overexpressing strain to partly mimic the biofilm defect of the fabR mutant, the effect of FabR on biofilms can be attributed at least partly to FabB, which plays a key role in UFA biosynthesis. Additionally, ChIP-chip identified a number of novel direct FabR targets (the intergenic regions between hpaR/hpaG and ddg/ydfZ) and yet putative direct targets (i.a. genes involved in tRNA metabolism, ribosome synthesis and translation). Next to UFA biosynthesis, a number of these direct targets and other indirect targets identified by transcriptomics (e.g. ribosomal genes, ompA, ompC, ompX, osmB, osmC, sseI), could possibly contribute to the effect of FabR on biofilm formation.
  
  
  CONCLUSIONS
  Overall, our results point at the importance of FabR and UFA biosynthesis in Salmonella biofilm formation and their role as potential targets for biofilm inhibitory strategies.
authors.affiliation: Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
authors.forename: Kim
authors.initials: K
authors.lastname: Hermans
authors.affiliation: Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Roberfroid
authors.affiliation: Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
authors.forename: Inge M
authors.initials: IM
authors.lastname: Thijs
authors.affiliation: Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
authors.forename: Gwendoline
authors.initials: G
authors.lastname: Kint
authors.affiliation: Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: De Coster
authors.affiliation: Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Marchal
authors.affiliation: Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
authors.forename: Jos
authors.initials: J
authors.lastname: Vanderleyden
authors.affiliation: Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.|Platform Biotechnology and Molecular Biology, Scientific Institute of Public Health (WIV-ISP), Brussels, Belgium.
authors.forename: Sigrid C J
authors.initials: SC
authors.lastname: De Keersmaecker
authors.affiliation: Department of Microbial and Molecular Systems, Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium. Hans.Steenackers@biw.kuleuven.be.
authors.forename: Hans P
authors.initials: HP
authors.lastname: Steenackers
mesh_terms: D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D047369:Chromatin Immunoprecipitation; D029968:Escherichia coli Proteins; D054889:Fatty Acid Synthase, Type II / Q000235:genetics / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis*; D015964:Gene Expression Regulation, Bacterial; D011401:Promoter Regions, Genetic; D018085:Regulon; D012486:Salmonella typhimurium / Q000235:genetics* / Q000254:growth & development; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D005231:Fatty Acids, Unsaturated; D014157:Transcription Factors; D015099:3-Oxoacyl-(Acyl-Carrier-Protein) Synthase; C490369:FabB protein, E coli; D054889:Fatty Acid Synthase, Type II
keywords: Biofilm; ChIP-chip; FabB; FabR; Salmonella; Unsaturated fatty acids