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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Xanthomonas citri T6SS mediates resistance to Dictyostelium predation and is regulated by an ECF sigma factor and cognate Ser/Thr kinase

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Bayer-Santos, Ethel [1] ; Lima, Lidia dos Passos [2] ; Ceseti, Lucas de Moraes [2] ; Ratagami, Camila Yuri [2] ; de Santana, Eliane Silva [2] ; da Silva, Aline Maria [1] ; Farah, Chuck Shaker [1] ; Alvarez-Martinez, Cristina Elisa [2]
Total Authors: 8
[1] Univ Sao Paulo, Inst Quim, Dept Bioquim, Sao Paulo - Brazil
[2] Univ Estadual Campinas, Inst Biol, Dept Genet Evolucao Microbiol & Imunol, Campinas, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: ENVIRONMENTAL MICROBIOLOGY; v. 20, n. 4, SI, p. 1562-1575, APR 2018.
Web of Science Citations: 6

Plant-associated bacteria of the genus Xanthomonas cause disease in a wide range of economically important crops. However, their ability to persist in the environment is still poorly understood. Predation by amoebas represents a major selective pressure to bacterial populations in the environment. In this study, we show that the X. citri type 6 secretion system (T6SS) promotes resistance to predation by the soil amoeba Dictyostelium discoideum. We found that an extracytoplasmic function (ECF) sigma factor (EcfK) is required for induction of T6SS genes during interaction with Dictyostelium. EcfK homologues are found in several environmental bacteria in association with a gene encoding a eukaryotic-like Ser/Thr kinase (pknS). Deletion of pknS causes sensitivity to amoeba predation and abolishes induction of T6SS genes. Phosphomimetic mutagenesis of EcfK identified a threonine residue (T51) that renders EcfK constitutively active in standard culture conditions. Moreover, susceptibility of Delta pknS to Dictyostelium predation can be overcome by expression of the constitutively active version EcfK(T51E) from a multicopy plasmid. Together, these results describe a new regulatory cascade in which PknS functions through activation of EcfK to promote T6SS expression. Our work reveals an important aspect of Xanthomonas physiology that affects its ability to persist in the environment. (AU)

FAPESP's process: 16/08400-6 - The effects of host plant extracts in Xanthomonas citri subsp citri physiology and protein secretion
Grantee:Camila Yuri Ratagami
Support type: Scholarships in Brazil - Scientific Initiation
FAPESP's process: 14/19720-6 - The Xanthomonas citri pv. citri type vi secretion system: function, gene regulation and secreted substrates
Grantee:Cristina Elisa Alvarez Martinez
Support type: Regular Research Grants
FAPESP's process: 14/25261-4 - Gene expression analysis of the Xanthomonas citri subsp citri type VI secretion system
Grantee:Lucas de Moraes Ceseti
Support type: Scholarships in Brazil - Scientific Initiation
FAPESP's process: 11/07777-5 - Cyclic di-GMP signaling and the Type IV macromolecule secretion system in Xanthomonas citri
Grantee:Shaker Chuck Farah
Support type: Research Projects - Thematic Grants
FAPESP's process: 15/25381-2 - Study of the role of type IV secretion system of Xanthomonas citri and Stenotrophomonas maltophilia in the interaction with Dictyostelium discoideum.
Grantee:Ethel Bayer Santos
Support type: Scholarships in Brazil - Post-Doctorate