Transcriptome analysis of Listeria monocytogenes identifies three groups of genes differently regulated by PrfA

Eliane Milohanic, Philippe Glaser, Jean-Yves Coppée, Lionel Franguel, Yolanda Vega, Jose Vazquez-Boland, Frank Kunst, Pascale Cossart, Carmen Buchrieser

Research output: Contribution to journalArticlepeer-review

Abstract

PrfA is the major regulator of Listeria virulence gene expression. This protein is a member of the Crp/Fnr family of transcription regulators. To gain a deeper understanding of the PrfA regulon, we constructed a whole-genome array based on the complete genome sequence of Listeria monocytogenes strain EGDe and evaluated the expression profiles of the wild-type EGDe and a prfA-deleted mutant (EGDe Delta prfA). Both strains were grown at 37 degrees C in brain-heart infusion broth (BHI) and BHI supplemented with either activated charcoal, a compound known to enhance virulence gene expression, or cellobiose, a sugar reported to downregulate virulence gene expression in spite of full expression of PrfA. We identified three groups of genes that are regulated differently. Group I comprises, in addition to the 10 already known genes, two new genes, lmo2219 and lmo0788, both positively regulated and preceded by a putative PrfA box. Group II comprises eight negatively regulated genes: lmo0278 is preceded by a putative PrfA box, and the remaining seven genes (lmo0178-lmo0184) are organized in an operon. Group III comprises 53 genes, of which only two (lmo0596 and lmo2067) are preceded by a putative PrfA box. Charcoal addition induced upregulation of group I genes but abolished regulation by PrfA of most group III genes. In the presence of cellobiose, all the group I genes were downregulated, whereas group III genes remained fully activated. Group II genes were repressed in all conditions tested. A comparison of the expression profiles between a second L. monocytogenes strain (P14), its spontaneous mutant expressing a constitutively active PrfA variant (P14prfA*) and its corresponding prfA-deleted mutant (P14 Delta prfA) and the EGDe strain revealed interesting strain-specific differences. Sequences strongly similar to a sigma B-dependent promoter were identified upstream of 22 group III genes. These results suggest that PrfA positively regulates a core set of 12 genes preceded by a PrfA box and probably expressed from a sigma A-dependent promoter. In contrast, a second set of PrfA-regulated genes lack a PrfA box and are expressed from a sigma B-dependent promoter. This study reveals that PrfA can act as an activator or a repressor and suggests that PrfA may directly or indirectly activate different sets of genes in association with different sigma factors.
Original languageEnglish
Pages (from-to)1613-25
Number of pages13
JournalMolecular Microbiology
Volume47
Issue number6
DOIs
Publication statusPublished - Mar 2003

Keywords

  • Bacterial Proteins/genetics
  • Bacterial Proteins/metabolism
  • Cell Division/genetics
  • Cellobiose/metabolism
  • Charcoal
  • Culture Media/chemistry
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial
  • Listeria monocytogenes/genetics
  • Listeria monocytogenes/metabolism
  • Mutation
  • Oligonucleotide Array Sequence Analysis
  • Peptide Termination Factors
  • Polymerase Chain Reaction/methods
  • Trans-Activators/genetics
  • Trans-Activators/metabolism
  • Transcription, Genetic

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