Xanthomonas citri explained

Xanthomonas citri is a Gram-negative, rod-shaped bacterium. Although it is harmless for humans, it is a phytopathogen, known for being the causing agent of citrus canker.

Bacterial killing via a secretion system

Xanthomonas citri uses its type IV secretion system to kill other Gram-negative bacterial species in a contact-dependent manner. The secretion of the effector proteins requires a conserved C-terminal domain, and its bacteriolytic activity is neutralized by a cognate immunity protein.^{[1] [2]}

Defense against predators

Xanthomonas citri also uses type VI secretion system in defense against the predatory amoeba Dictyostelium discoideum.^[3]

Notes and References

1. Souza DP, Oka GU, Alvarez-Martinez CE, Bisson-Filho AW, Dunger G, Hobeika L, Cavalcante NS, Alegria MC, Barbosa LR, Salinas RK, Guzzo CR, Farah CS . Bacterial killing via a type IV secretion system . Nature Communications . 6 . 6453 . 2015 . 25743609 . 10.1038/ncomms7453 . 2015NatCo...6.6453S . free .
2. Sgro GG, Costa TR, Cenens W, Souza DP, Cassago A, Coutinho de Oliveira L, Salinas RK, Portugal RV, Farah CS, Waksman G . Cryo-EM structure of the bacteria-killing type IV secretion system core complex from Xanthomonas citri . Nature Microbiology . 3. 1429–1440. 2018 . 12 . 30349081 . 10.1038/s41564-018-0262-z . 6264810 .
3. Bayer-Santos. Ethel. Lima. Lídia dos Passos. Ceseti. Lucas de Moraes. Ratagami. Camila Yuri. de Santana. Eliane Silva. da Silva. Aline Maria. Farah. Chuck Shaker. Alvarez-Martinez. Cristina Elisa. Xanthomonas citri T6SS mediates resistance to Dictyostelium predation and is regulated by an ECF σ factor and cognate Ser/Thr kinase. Environmental Microbiology. 20. 4. 2018. 1562–1575. 1462-2912. 10.1111/1462-2920.14085. 29488354. 3579518.