title: The diguanylate cyclase YddV controls production of the exopolysaccharide poly-N-acetylglucosamine (PNAG) through regulation of the PNAG biosynthetic pgaABCD operon.
abstract: In Gram-negative bacteria, production of adhesion factors and extracellular polysaccharides (EPS) is promoted by the activity of diguanylate cyclases (DGCs), a class of enzymes able to catalyse the synthesis of the signal molecule bis-(3',5')-cyclic di-guanylic acid (c-di-GMP). In this report we show that in Escherichia coli, overexpression of the YddV protein, but not of other DGCs such as AdrA and YcdT, induces the production of the EPS poly-N-acetylglucosamine (PNAG) by stimulating expression of pgaABCD, the PNAG-biosynthetic operon. Stimulation of PNAG production and activation of pgaABCD expression by the YddV protein are abolished by inactivation of its GGDEF motif, responsible for DGC activity. Consistent with the effects of YddV overexpression, inactivation of the yddV gene negatively affects pgaABCD transcription and PNAG-mediated biofilm formation. pgaABCD regulation by the yddV gene also takes place in a mutant carrying a partial deletion of the csrA gene, which encodes the main regulator of pgaABCD expression, suggesting that YddV does not regulate pgaABCD through modulation of CsrA activity. Our results demonstrate that PNAG production does not simply respond to intracellular c-di-GMP concentration, but specifically requires the DGC activity of the YddV protein, thus supporting the notion that in E. coli, c-di-GMP biosynthesis by a given DGC protein triggers regulatory events that lead to activation of specific sets of EPS biosynthetic genes or proteins.
authors.affiliation: Department of Biomolecular Sciences and Biotechnology, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy.
authors.forename: Letizia
authors.initials: L
authors.lastname: Tagliabue
authors.affiliation: Department of Biomolecular Sciences and Biotechnology, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Antoniani
authors.affiliation: Department of Biomolecular Sciences and Biotechnology, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Maciąg
authors.affiliation: Department of Molecular Pathology and Innovative Therapies, Section of Biochemistry, Università Politecnica delle Marche, Via Ranieri, 60131 Ancona, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Bocci
authors.affiliation: Department of Molecular Pathology and Innovative Therapies, Section of Biochemistry, Università Politecnica delle Marche, Via Ranieri, 60131 Ancona, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Raffaelli
authors.affiliation: Department of Biomolecular Sciences and Biotechnology, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Landini
mesh_terms: D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D019761:Phosphorus-Oxygen Lyases / Q000235:genetics / Q000378:metabolism*; D047071:beta-Glucans / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D047071:beta-Glucans; C505465:poly-N-acetyl-1-6-glucosamine; D019761:Phosphorus-Oxygen Lyases; C553251:yddV protein, E coli