title: N-Acetylglucosamine-dependent biofilm formation in Pectobacterium atrosepticum is cryptic and activated by elevated c-di-GMP levels.
abstract: The phytopathogenic bacterium Pectobacterium atrosepticum (Pba) strain SCRI1043 does not exhibit appreciable biofilm formation under standard laboratory conditions. Here we show that a biofilm-forming phenotype in this strain could be activated from a cryptic state by increasing intracellular levels of c-di-GMP, through overexpression of a constitutively active diguanylate cyclase (PleD*) from Caulobacter crescentus. Randomly obtained Pba transposon mutants defective in the pga operon, involved in synthesis and translocation of poly-β-1,6-N-acetyl-D-glucosamine (PGA), were all impaired in this biofilm formation. The presence of the PGA-degrading enzyme dispersin B in the growth media prevented biofilm formation by Pba overexpressing PleD*, further supporting the importance of PGA for biofilm formation by Pba. Importantly, a pga mutant exhibited a reduction in root binding to the host plant under conditions of high intracellular c-di-GMP levels. A modest but consistent increase in pga transcript levels was associated with high intracellular levels of c-di-GMP. Our results indicate tight control of PGA-dependent biofilm formation by c-di-GMP in Pba.
authors.affiliation: Departamento de Microbiología del suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, C/ Profesor Albareda 1, 18008 Granada, Spain.|Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Pérez-Mendoza
authors.affiliation: Division of Molecular Microbiology, University of Dundee, Dundee DD1 5EH, UK.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Coulthurst
authors.affiliation: Departamento de Microbiología del suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, C/ Profesor Albareda 1, 18008 Granada, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Sanjuán
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.
authors.forename: George P C
authors.initials: GPC
authors.lastname: Salmond
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D016935:Caulobacter crescentus / Q000201:enzymology / Q000235:genetics; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D004251:DNA Transposable Elements; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D016254:Mutagenesis, Insertional; D044043:Pectobacterium / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics
chemical_list: D004251:DNA Transposable Elements; D011994:Recombinant Proteins; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP; D000117:Acetylglucosamine