A cyclic GMP-dependent signalling pathway regulates bacterial phytopathogenesis |
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Authors: | Shi-Qi An Ko-Hsin Chin Melanie Febrer Yvonne McCarthy Jauo-Guey Yang Chung-Liang Liu David Swarbreck Jane Rogers J Maxwell Dow Shan-Ho Chou Robert P Ryan |
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Affiliation: | 1Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee, UK;2Agricultural Biotechnology Center, Institute of Biochemistry, National Chung Hsing University, Taichung, Taiwan, ROC;3Division of Molecular Medicine, Colleges of Life Sciences, University of Dundee, Dundee, UK;4Department of Microbiology, Biosciences Institute, University College Cork, Cork, Ireland;5The Genome Analysis Centre, Norwich, UK |
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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. |
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Keywords: | biofilm cyclic di‐GMP signal transduction virulence Xanthomonas campestris |
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