1. A Ralstonia solanacearum type III effector alters the actin and microtubule cytoskeleton to promote bacterial virulence in plants.
- Author
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Hiles, Rachel, Rogers, Abigail, Jaiswal, Namrata, Zhang, Weiwei, Butchacas, Jules, Merfa, Marcus V., Klass, Taylor, Barua, Pragya, Thirumalaikumar, Venkatesh P., Jacobs, Jonathan M., Staiger, Christopher J., Helm, Matthew, and Iyer-Pascuzzi, Anjali S.
- Subjects
PLANT cytoskeleton ,CELL anatomy ,PHYTOPATHOGENIC microorganisms ,PATHOGENIC bacteria ,PLANT colonization ,BACTERIAL wilt diseases ,RALSTONIA solanacearum - Abstract
Cellular responses to biotic stress frequently involve signaling pathways that are conserved across eukaryotes. These pathways include the cytoskeleton, a proteinaceous network that senses external cues at the cell surface and signals to interior cellular components. During biotic stress, dynamic cytoskeletal rearrangements serve as a platform from which early immune-associated processes are organized and activated. Bacterial pathogens of plants and animals use proteins called type III effectors (T3Es) to interfere with host immune signaling, thereby promoting virulence. We previously found that RipU, a T3E from the soilborne phytobacterial pathogen Ralstonia solanacearum, co-localizes with the plant cytoskeleton. Here, we show that RipU from R. solanacearum K60 (RipU
K60 ) associated with and altered the organization of both the actin and microtubule cytoskeleton. We found that pharmacological disruption of the tomato (Solanum lycopersicum) cytoskeleton promoted R. solanacearum K60 colonization. Importantly, tomato plants inoculated with R. solanacearum K60 lacking RipUK60 (ΔripUK60 ) had reduced wilting symptoms and significantly reduced root colonization when compared to plants inoculated with wild-type R. solanacearum K60. Collectively, our data suggest that R. solanacearum K60 uses the type III effector RipUK60 to remodel cytoskeletal organization, thereby promoting pathogen virulence. Author summary: Pathogenic bacteria secrete dozens of proteins directly into plant and animal cells to interfere with host biology and promote disease. These proteins, termed effectors, target different host proteins to alter cellular processes and enable pathogen virulence. Understanding how distinct effectors manipulate host proteins is critical for developing new disease control strategies. The cytoskeleton is a protein network found across eukaryotic organisms that can sense external signals and transmit responses to the cell interior. Dynamic reorganization of the cytoskeleton is required for immune signaling. Here we showed that the cytoskeleton is critical for resistance to the soilborne phytobacterial pathogen Ralstonia solanacearum. We found that RipU, an R. solanacearum effector protein, physically associates with and alters the organization of the actin and microtubule cytoskeleton in plants. We also found that RipU is required for full pathogen virulence. While an R. solanacearum mutant that is defective in ripU is unable to cause disease at the same level as wild type R. solanacearum, chemical disruption of the cytoskeleton restored full virulence to these mutants. Our study provides new insights into how pathogenic bacteria manipulate cellular targets to cause disease. [ABSTRACT FROM AUTHOR]- Published
- 2024
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