Poster Presentation BacPath 13: Molecular Analysis of Bacterial Pathogens Conference 2015

Identifying the host targets of putative glycosyltransferase effectors from Salmonella (#207)

Joshua P.M. Newson 1 , Tania Wong 1 , Vicki Bennett-Wood 1 , Laura Dagley 2 , Doreen Agyapomaa 2 , Nat F. Brown 3 , Andrew Webb 2 , Jaclyn S. Pearson 1 , Elizabeth L. Hartland 1
  1. Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, VIC, Australia
  2. Division of Systems Biology and Personalised Medicine, Walter and Eliza Hall Institute, Melbourne, VIC, Australia
  3. Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada

Pathogenic serovars of Salmonella are the causative agents of a variety of disease states, including typhoid fever, self-limiting gastroenteritis, and invasive bacteremia. Pathogenesis is dependent on the activity of two distinct type III secretion systems (T3SS), encoded by genetic regions termed Salmonella pathogenicity islands (SPI). Effector proteins secreted by the SPI-1 T3SS play important roles in colonisation of the gastrointestinal tract, while effectors of the SPI-2 T3SS are involved in intracellular persistence, and the establishment of the Salmonella-containing vacuole (SCV), a critical replicative niche. However, many of the SPI-2 encoded effector proteins remain poorly characterised. Our work focuses on the SseK family of SPI-2 effector proteins, consisting of SseK1, SseK2 and SseK3. The SseK family is homologous to the NleB effector from enteropathogenic E. coli, which was recently reported to be a novel glycosyltransferase that adds a single N-acetylglucosamine to human FADD, blocking the host apoptotic pathway. We predict the SseK proteins have similar enzymatic activity, however we have established that FADD is not the target. Therefore, the aim of our work is to characterise the role of the SseKs in Salmonella infection, and to identify putative targets from the host cell. We describe here the subcellular localisation of the SseK proteins in HeLa cells in both transfection and infection experiments. SseK1 predominantly localises to the nucleus, while SseK2 and SseK3 localise predominantly with the Golgi apparatus, suggesting that these proteins may have some interaction with host Golgi proteins. Additionally, SseK3 extends along the Salmonella induced filament structures and cells of this phenotype have disrupted Golgi apparatus. These preliminary data show the SseK proteins have different subcellular localisation phenotypes, and may suggest possible roles in Salmonella infection. We intend to advance the understanding of the SseK proteins by identifying binding partners through immunoprecipitation, mass spectrometry and yeast two-hybrid screens.