title: Dual role of CcpC protein in regulation of aconitase gene expression in Listeria monocytogenes and Bacillus subtilis.
abstract: The role of the CcpC regulatory protein as a repressor of the genes encoding the tricarboxylic acid branch enzymes of the Krebs cycle (citrate synthase, citZ; aconitase, citB; and isocitrate dehydrogenase, citC) has been established for both Bacillus subtilis and Listeria monocytogenes. In addition, hyperexpression of citB-lacZ reporter constructs in an aconitase null mutant strain has been reported for B. subtilis. We show here that such hyperexpression of citB occurs in L. monocytogenes as well as in B. subtilis and that in both species the hyperexpression is unexpectedly dependent on CcpC. We propose a revision of the existing CcpC-citB regulatory scheme and suggest a mechanism of regulation in which CcpC represses citB expression at low citrate levels and activates citB expression when citrate levels are high.
authors.affiliation: Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: Meghna
authors.initials: M
authors.lastname: Mittal
authors.affiliation: Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: Kieran B
authors.initials: KB
authors.lastname: Pechter
authors.affiliation: Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: Silvia
authors.initials: S
authors.lastname: Picossi
authors.affiliation: Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: Hyun-Jin
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: Kathryn O
authors.initials: KO
authors.lastname: Kerstein
authors.affiliation: Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA.|Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA.
authors.forename: Abraham L
authors.initials: AL
authors.lastname: Sonenshein
mesh_terms: D000154:Aconitate Hydratase / Q000096:biosynthesis*; D019677:Artificial Gene Fusion; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D008089:Listeria monocytogenes / Q000201:enzymology* / Q000235:genetics*; D012097:Repressor Proteins / Q000378:metabolism*; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D012097:Repressor Proteins; D001616:beta-Galactosidase; D000154:Aconitate Hydratase