title: Cross communication between components of carbon catabolite repression of Lactobacillus casei and Bacillus megaterium.
abstract: In low-GC Gram-positive bacteria, carbon catabolite repression (CCR) is exerted by transcriptional regulation through a protein complex consisting of catabolite control protein CcpA and serine phosphorylated phosphocarrier protein HPr (HPr-ser-P). We investigated the interaction between these components of Lactobacillus casei and Bacillus megaterium. CcpA of L. casei could not complement a B. megaterium ccpA mutant strain, whereas it was found to be functional in Bacillus subtilis. To explore the nature of the non-complementing phenotype, we overproduced and purified CcpA and HPr of L. casei for in vitro analyses. Electrophoretic mobility shift assays revealed a failure in CCR signal transduction at the level of protein-protein interaction between L. casei CcpA and B. megateriumHPr-ser-P, while binding of CcpA to the B. megaterium target site was intact. We established a method based on surface plasmon resonance that allowed a quantitative analysis of CcpA/HPr-ser-P interactions. Calculation of the apparent dissociation constants revealed that the interaction of L. casei CcpA with B. megaterium HPr-ser-P was fivefold weaker than with its own HPr-ser-P suggesting that the reduced affinity was responsible for the non-complementing phenotype.
authors.affiliation: Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Mahr
authors.forename: Carlos David
authors.initials: CD
authors.lastname: Esteban
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hillen
authors.forename: Fritz
authors.initials: F
authors.lastname: Titgemeyer
authors.forename: Gaspar
authors.initials: G
authors.lastname: Pérez-Martínez
mesh_terms: D001410:Bacillus megaterium / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins / Q000502:physiology*; D024202:Electrophoretic Mobility Shift Assay; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005816:Genetic Complementation Test; D007780:Lacticaseibacillus casei / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000502:physiology*; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; C069286:catabolite control proteins, bacteria; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr