title: A cyclic GMP-dependent signalling pathway regulates bacterial phytopathogenesis.
abstract: Cyclic guanosine 3',5'-monophosphate (cyclic GMP) is a second messenger whose role in bacterial signalling is poorly understood. A genetic screen in the plant pathogen Xanthomonas campestris (Xcc) identified that XC_0250, which encodes a protein with a class III nucleotidyl cyclase domain, is required for cyclic GMP synthesis. Purified XC_0250 was active in cyclic GMP synthesis in vitro. The linked gene XC_0249 encodes a protein with a cyclic mononucleotide-binding (cNMP) domain and a GGDEF diguanylate cyclase domain. The activity of XC_0249 in cyclic di-GMP synthesis was enhanced by addition of cyclic GMP. The isolated cNMP domain of XC_0249 bound cyclic GMP and a structure-function analysis, directed by determination of the crystal structure of the holo-complex, demonstrated the site of cyclic GMP binding that modulates cyclic di-GMP synthesis. Mutation of either XC_0250 or XC_0249 led to a reduced virulence to plants and reduced biofilm formation in vitro. These findings describe a regulatory pathway in which cyclic GMP regulates virulence and biofilm formation through interaction with a novel effector that directly links cyclic GMP and cyclic di-GMP signalling.
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee, UK.
authors.forename: Shi-Qi
authors.initials: SQ
authors.lastname: An
authors.forename: Ko-Hsin
authors.initials: KH
authors.lastname: Chin
authors.forename: Melanie
authors.initials: M
authors.lastname: Febrer
authors.forename: Yvonne
authors.initials: Y
authors.lastname: McCarthy
authors.forename: Jauo-Guey
authors.initials: JG
authors.lastname: Yang
authors.forename: Chung-Liang
authors.initials: CL
authors.lastname: Liu
authors.forename: David
authors.initials: D
authors.lastname: Swarbreck
authors.forename: Jane
authors.initials: J
authors.lastname: Rogers
authors.forename: J
authors.initials: J
authors.lastname: Maxwell Dow
authors.forename: Shan-Ho
authors.initials: SH
authors.lastname: Chou
authors.forename: Robert P
authors.initials: RP
authors.lastname: Ryan
mesh_terms: D000704:Analysis of Variance; D001426:Bacterial Proteins / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development; D002151:Calorimetry; D002851:Chromatography, High Pressure Liquid; D006152:Cyclic GMP / Q000096:biosynthesis / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D008958:Models, Molecular; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015290:Second Messenger Systems / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D014774:Virulence; D016959:Xanthomonas campestris / Q000472:pathogenicity / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D006152:Cyclic GMP