IBBM   21076
INSTITUTO DE BIOTECNOLOGIA Y BIOLOGIA MOLECULAR
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
c-di-GMP enhanced biofilm formation in Bordetella bronchiseptica is not BvgA regulated
Autor/es:
FERNANDEZ, JULIETA; HOZBOR, DANIELA; SISTI, FEDERICO
Lugar:
San Miguel de Tucumán
Reunión:
Congreso; Congreso 2011 VII CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL SAMIGE DEL BICENTENARIO; 2011
Institución organizadora:
Sociedad Argentina de Microbiología General
Resumen:
Cyclic diguanylate (or bis-(3´-5´) cyclic dimeric guanosine monophosphate; c-di-GMP) is a ubiquitous second messenger that regulates diverse cellular functions, including motility, biofilm formation, cell cycle progression, and virulence in bacteria. C-di-GMP is produced from two molecules of GTP by diguanylate cyclase. Enzyme activity is conferred with the GGDEF functional domain whereas c-di-GMP-specific phosphodiesterase activity is carried out by EAL or HD-GYP domains. Notably, bacterial genomes frequently encode numerous GGDEF and EAL/HD-GYP proteins, implying that the c-di-GMP network is a highly complex and tightly regulated intracellular signalling system. Most GGDEF and EAL domains are linked directly to a two component phosphorylation cascade. Bordetella bronchiseptica is a pathogenic bacterium that causes respiratory infections in a wide variety of host. Most known virulence factors in Bordetella are regulated by the BvgAS two component signal transduction system. In response to external signals, BvgAS undergoes a series of phosphorelay signal transduction events that ultimately lead to differential transcription of genes. This phenotypic modulation results in virulent, intermediate and avirulent phases. This system also regulates biofilm formation in B. bronchiseptica and intermediate phase is the one with maximum formation of biofilm. In a previous work we separately transformed B. bronchiseptica with heterologous genes from Pseudomonas aeruginosa coding for reported EAL or GGDEF proteins (PA3947 and PA1120) and determined that high c-di-GMP enhances biofilm formation and decreases motility in B. bronchiseptica. In the present work we evaluate a possible relation between c-di-GMP network and BvgAS system. PA3947 and PA1120 were introduced in a B. bronchiseptica mutant blocked in avirulent phase (BbBvgA-), and thus unable to modulate between phases. Biofilm formation was evaluated in the recombinant and parental strain in presence of different concentrations of known BvgAS system regulating signals (nicotinic acid and magnesium sulfate), which induce expression of different phases. Parental strain with a functional BvgAS system presents hyperbiofilm formation in intermediate phase as expected. In absence of BvgA in BbBvgA-, biofilm phenotype corresponds to the observed in avirulent phase despite modulators presence. Surprisingly, BbBvgA- expressing PA1120 corresponding to high c-di-GMP concentration, exhibited a biofilm formation behavior similar to the parental strain, with maximal formation in presence of signals concentration corresponding to intermediate phase. These results showed that although both systems are necessary for biofilm formation, diguanilate cyclase expression in B. bronchiseptica allowed biofilm formation in BvgA regulation absence.