| Talk title | Identification and characterization of type III secretion system (T3SS) effectors in Edwardsiella piscicida |
| Speaker | Prof. Kayin Leung Professor Guangdong Technion – Israel Institute of Technology |
| Date & Time | 26 October 2018 (Fri) 10:00am-11:00am |
| Venue | Room G003, E12 Building (University of Macau) |
| Abstract | Edwardsiella piscicida (old name as E. tarda) has a board host range and causes severe fish losses in aquaculture worldwide. The type III and type VI secretion system (T3SS and T6SS) are the bacterium’s most lethal weapons against the host defense. My laboratory discovered a T3SS and a T6SS in E. piscicida; mutations in these gene clusters resulted in severe virulence attenuation. T3SS effector proteins are directly inject into host cells through nano-secretion machineries called injectisomes. These effectors have diverse functions that target specific host proteins to disrupt and mimic host cellular processes, and then interfere with the host immunity. One area of my research is to identify effectors of T3SS and characterize them individually and collectively in order to understand their unique functions. We have used several approaches to identify Edwardsiella T3SS effectors, such as transcriptome analysis, homology search, and machine learning. Our effector prediction program gave better performance values and predicts more effectors in four tested bacterial genomes. The next step is to train our algorithms for family- or species-specific T3SS effector prediction and then apply the program to Edwardsiella strains. Characterization of effectors can use several approaches such as the identification of targeted proteins in hosts, location of effectors inside the host cell, or screening against known virulent phenotypes. For example, we found a microtubule disassembly phenotype upon Edwardsiella infection of HeLa cells. We screened for this phenotype against a defined transposon mutant library of ~2,700+ mutants and obtained 15 genes that were responsible for the microtubule disassembly phenotype. Effector studies in Edwardsiella will generate important fundamental knowledge on host-pathogen interactions. This information will be useful for vaccine, novel therapeutics and diagnostics development. |
