Transcriptome Analysis of Listeria Monocytogenes Identifies Three Groups of Genes Differently Regulated by PrfA

Mol Microbiol. 2003 Mar;47(6):1613-25. doi: 10.1046/j.1365-2958.2003.03413.x.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 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

Substances

  • Bacterial Proteins
  • Culture Media
  • Peptide Termination Factors
  • Trans-Activators
  • Charcoal
  • Cellobiose