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

Autor(es)

Bayer-Santos, Ethel ; Lima, Lidia dos Passos ; Ceseti, Lucas de Moraes ; Ratagami, Camila Yuri ; de Santana, Eliane Silva ; da Silva, Aline Maria ; Farah, Chuck Shaker ; Alvarez-Martinez, Cristina Elisa

• Tipo de documento: Artigo Científico
• Fonte: ENVIRONMENTAL MICROBIOLOGY; v. 20, n. 4, p. 14-pg., 2018-04-01.

Resumo

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)

• Processo FAPESP: 15/25381-2 - Estudo do papel dos sistemas de secreção do tipo IV de Xanthomonas citri e Stenotrophomonas maltophilia na interação com Dictyostelium discoideum.
• Beneficiário: Ethel Bayer Santos
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 16/08400-6 - Efeitos de extratos de planta hospedeira na fisiologia e secreção de proteínas em Xanthomonas citri subsp citri
• Beneficiário: Camila Yuri Ratagami
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica
• Processo FAPESP: 11/07777-5 - Sinalização por c-di-GMP e o sistema de secreção de macromoléculas do tipo IV em Xanthomonas citri
• Beneficiário: Shaker Chuck Farah
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 14/19720-6 - O sistema de secreção do tipo VI de Xanthomonas citri pv. citri: função, regulação e substratos secretados
• Beneficiário: Cristina Elisa Alvarez Martinez
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 14/25261-4 - Análise da expressão gênica de componentes do sistema de secreção do tipo VI de Xanthomonas citri subsp citri
• Beneficiário: Lucas de Moraes Ceseti
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica