Prof. Dr. Martin Aepfelbacher, Universitätsklinikum Hamburg Eppendorf, Hamburg, Germany
Title of the talk:
Visualization and new functions of the Yersinia injectisome
Many human, animal and plant pathogenic bacteria including Chlamydia, Pseudomonas, EPEC and EHEC, Salmonella, Shigella and Yersinia employ a molecular machine termed injectisome to inject their effector-toxins into host cells. The biochemical activities of these effectors often are unique, multifaceted and reflect the infection strategies of the individual pathogens. Injectisomes are highly similar between the different bacteria and most of their overall structure is well established at the molecular level. However, only little information is available for a central part of the injectisome named the translocon. This pore-like assembly integrates into host cell membranes and serves as an entry gate for the bacterial toxins. We employed state of the art fluorescence microscopy to watch translocon proteins of the diarrheagenic pathogen Yersinia enterocolitica during infection of human host cells. Thereby we could visualize the translocons connected to other parts of the injectisome and also demonstrate that their number produced during infection depends on specific host cell factors and is in turn regulated by bacterial effectors. Furthermore, translocons only became active when the bacteria were almost completely enclosed by host cells and resided in a specific host cell compartment named a prevacuole.
Prof. Dr. Martin Aepfelbacher is the director of the Institute for Medical Microbiology, Virology and Hygiene at the University Medical Centre Hamburg-Eppendorf, currently one of the most modern hospitals in Europe (opened in February 2009). Research in the Aepfelbacher lab focuses on the cellular microbiology of the bacterial pathogens Yersinia enterocolitica and Staphylococcus aureus, the effect of bacterial toxins on the human vascular endothelium and the cell biology of macrophages.