An Extracytoplasmic Function Sigma Factor Required for Full Virulence in Xanthomonas citri pv. citri

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Lima, Lidia dos Passos ; Pereira, Juliana Biar ; Fasabi Flores, Anthony Jhoao ; Rodrigues Lorenzetti, Alan Pericles ; Boechat, Ana Laura ; Pereda, Maria Claudia ; Gualtieri, Sophia ; do Prado, Daniele Ferreira ; Rocha, Diego ; Ceseti, Lucas de Moraes ; Baldini, Regina Lucia ; Farah, Chuck S. ; Koide, Tie ; Benedetti, Celso Eduardo ; Alvarez-Martinez, Cristina E.

• Tipo de documento: Artigo Científico
• Fonte: Journal of Bacteriology; v. 204, n. 5, p. 19-pg., 2022-04-21.

Resumo

The genus Xanthomonas includes more than 30 phytopathogenic species that infect a wide range of plants and cause severe diseases that greatly impact crop productivity. These bacteria are highly adapted to the soil and plant environment, being found in decaying material, as epiphytes, and colonizing the plant mesophyll. Signal transduction mechanisms involved in the responses of Xanthomonas to environmental changes are still poorly characterized. Xanthomonad genomes typically encode several representatives of the extracytoplasmic function sigma (sigma(ECF)) factors, whose physiological roles remain elusive. In this work, we functionally characterized the Xanthomonas citri pv. citri EcfL, a sigma(ECF) factor homologous to members of the iron-responsive FecI-like group. We show that EcfL is not required or induced during iron starvation, despite presenting the common features of other FecI-like sigma(ECF) factors. EcfL positively regulates one operon composed of three genes that encode a TonB-dependent receptor involved in cell surface signaling, an acid phosphatase, and a lectin-domain containing protein. Furthermore, we demonstrate that EcfL is required for full virulence in citrus, and its regulon is induced inside the plant mesophyll and in response to acid stress. Together, our study suggests a role for EcfL in the adaptation of X. citri to the plant environment, in this way contributing to its ability to cause citrus canker disease. IMPORTANCE The Xanthomonas genus comprises a large number of phytopathogenic species that infect a wide variety of economically important plants worldwide. Bacterial adaptation to the plant and soil environment relies on their repertoire of signal transduction pathways, including alternative sigma factors of the extracytoplasmic function family (sigma(ECF)). Here, we describe a new sigma(ECF) factor found in several Xanthomonas species, demonstrating its role in Xanthomonas citri virulence to citrus plants. We show that EcfL regulates a single operon containing three genes, which are also conserved in other Xanthomonas species. This study further expands our knowledge on the functions of the widespread family of sigma(ECF) factors in phytopathogenic bacteria. (AU)

• Processo FAPESP: 18/01852-4 - Estudos Funcionais do Sistema de Secreção do Tipo VI e da Regulação Gênica por Fatores Sigma Alternativos em Xanthomonas citri
• Beneficiário: Cristina Elisa Alvarez Martinez
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 17/03052-2 - RNAs não codificantes derivados de sequências de inserção na arqueia halófila Halobacterium salinarum NRC-1
• Beneficiário: Alan Péricles Rodrigues Lorenzetti
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 04/10916-3 - Estudo funcional dos fatores sigma de RNA polimerase do fitopatógeno Xanthomonas axonopodis pv. citri
• Beneficiário: Maria Claudia Pereda Rosa
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 19/03406-4 - Caracterização funcional do regulon do fator sigma alternativo EcfL de Xanthomonas citri subsp. citri
• Beneficiário: Anthony Jhoao Fasabi Flores
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 17/02318-9 - Estudos funcionais do sistema de secreção do tipo VI de Xanthomonas citri subsp. citri: identificação de proteínas secretadas, mecanismos de recrutamento e regulação do sistema
• Beneficiário: Lucas de Moraes Ceseti
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto