title: Expression of the agmatine deiminase pathway in Enterococcus faecalis is activated by the AguR regulator and repressed by CcpA and PTS(Man) systems.
abstract: Although the agmatine deiminase system (AgDI) has been investigated in Enterococcus faecalis, little information is available with respect to its gene regulation. In this study we demonstrate that the presence of exogenous agmatine induces the expression of agu genes in this bacterium. In contrast to the homologous and extensively characterized AgDI system of S. mutants, the aguBDAC operon in E. faecalis is not induced in response to low pH. In spite of this, agmatine catabolism in this bacterium contributes by neutralizing the external medium while enhancing bacterial growth. Our results indicate that carbon catabolic repression (CCR) operates on the AgDI system via a mechanism that involves interaction of CcpA and P-Ser-HPr with a cre site found in an unusual position considering the aguB promoter (55 nt upstream the +1 position). In addition, we found that components of the mannose phosphotransferase (PTS(Man)) system also contributed to CCR in E. faecalis since a complete relief of the PTS-sugars repressive effect was observed only in a PTS(Man) and CcpA double defective strain. Our gene context analysis revealed that aguR is present in oral and gastrointestinal microorganisms. Thus, regulation of the aguBDAC operon in E. faecalis seems to have evolved to obtain energy and resist low pH conditions in order to persist and colonize gastrointestinal niches.
authors.affiliation: Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas (IBR-CONICET), Rosario, Santa Fe, Argentina ; Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina.
authors.forename: Cristian
authors.initials: C
authors.lastname: Suárez
authors.forename: Martín
authors.initials: M
authors.lastname: Espariz
authors.forename: Víctor S
authors.initials: VS
authors.lastname: Blancato
authors.forename: Christian
authors.initials: C
authors.lastname: Magni
mesh_terms: D000376:Agmatine / Q000378:metabolism; D064751:Ammonium Compounds / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D013293:Enterococcus faecalis / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics; D056426:Genetic Loci / Q000235:genetics; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000378:metabolism*; D008358:Mannose / Q000378:metabolism*; D053858:Metabolic Networks and Pathways / Q000235:genetics; D008954:Models, Biological; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D064751:Ammonium Compounds; D001426:Bacterial Proteins; D012097:Repressor Proteins; D000376:Agmatine; D017853:Phosphotransferases (Alcohol Group Acceptor); D006867:Hydrolases; D001616:beta-Galactosidase; C019626:agmatine deiminase; D008358:Mannose