Legionella pneumophila is a gram-negative bacteria that utilizes a type IV secretion system to alter its intracellular trafficking in host macrophages. Internalized Legionella containing vacuoles (LCV) immediately avoid transport to lysosomes and within 15 minutes of internalization, begin remodeling their phagosomal compartment with ER-derived host cell vesicles. Dot/icm mutants are efficiently transported to and fuse with lysosomes suggesting that the type IV secretion apparatus is required for altered LCV trafficking and remodeling. Identification of factors utilized by Legionella to alter trafficking and remodel its intracellular vacuole may provide new targets for therapeutic intervention. Furthermore, understanding how ER-derived vesicles are recruited to and fuse with a membrane-bound compartment originating from the plasma membrane may provide insight into novel host cell functions. Confocal microscopy, coimmunprecipitation studies, 2D-gel electrophoresis and in vitro budding and fusion reactions will be used to identify host and/or Legionella derived SNARE-like molecules that play a role in ER-derived vesicle fusion with LCV.
