title: Catabolite control protein E (CcpE) is a LysR-type transcriptional regulator of tricarboxylic acid cycle activity in Staphylococcus aureus.
abstract: The tricarboxylic acid cycle (TCA cycle) is a central metabolic pathway that provides energy, reducing potential, and biosynthetic intermediates. In Staphylococcus aureus, TCA cycle activity is controlled by several regulators (e.g. CcpA, CodY, and RpiRc) in response to the availability of sugars, amino acids, and environmental stress. Developing a bioinformatic search for additional carbon catabolite-responsive regulators in S. aureus, we identified a LysR-type regulator, catabolite control protein E (CcpE), with homology to the Bacillus subtilis CcpC regulator. Inactivation of ccpE in S. aureus strain Newman revealed that CcpE is a positive transcriptional effector of the first two enzymes of the TCA cycle, aconitase (citB) and to a lesser extent citrate synthase (citZ). Consistent with the transcriptional data, aconitase activity dramatically decreased in the ccpE mutant relative to the wild-type strain. The effect of ccpE inactivation on citB transcription and the lesser effect on citZ transcription were also reflected in electrophoretic mobility shift assays where CcpE bound to the citB promoter but not the citZ promoter. Metabolomic studies showed that inactivation of ccpE resulted in increased intracellular concentrations of acetate, citrate, lactate, and alanine, consistent with a redirection of carbon away from the TCA cycle. Taken together, our data suggest that CcpE is a major direct positive regulator of the TCA cycle gene citB.
authors.affiliation: From the Institute of Medical Microbiology and Hygiene, University of Saarland Hospital, 66421 Homburg/Saar, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Hartmann
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: Grégory
authors.initials: G
authors.lastname: Baronian
authors.forename: Bettina
authors.initials: B
authors.lastname: Schulthess
authors.forename: Dagmar
authors.initials: D
authors.lastname: Homerova
authors.forename: Stephanie
authors.initials: S
authors.lastname: Grubmüller
authors.forename: Erika
authors.initials: E
authors.lastname: Kutzner
authors.forename: Rosmarie
authors.initials: R
authors.lastname: Gaupp
authors.forename: Ralph
authors.initials: R
authors.lastname: Bertram
authors.forename: Robert
authors.initials: R
authors.lastname: Powers
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Eisenreich
authors.forename: Jan
authors.initials: J
authors.lastname: Kormanec
authors.forename: Mathias
authors.initials: M
authors.lastname: Herrmann
authors.forename: Virginie
authors.initials: V
authors.lastname: Molle
authors.forename: Greg A
authors.initials: GA
authors.lastname: Somerville
authors.forename: Markus
authors.initials: M
authors.lastname: Bischoff
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002952:Citric Acid Cycle / Q000235:genetics*; D017353:Gene Deletion; D056426:Genetic Loci / Q000235:genetics; D055442:Metabolome; D008969:Molecular Sequence Data; D012097:Repressor Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C069286:catabolite control proteins, bacteria; C073470:LysR protein, Bacteria
keywords: Bacterial Metabolism; Metabolic Regulation; Staphylococcus aureus; Transcription Regulation; Tricarboxylic Acid (TCA) Cycle