Isolation of the Dot/Icm Type IV Secretion System Core Complex from Legionella pneumophila.

Legionella utilizes specialized protein secretion machinery called the type IV secretion system encoded by dot/icm genes to modulate host cellular systems. We describe here the procedure to isolate the core complex of the Dot/Icm type IV secretion system of L. pneumophila based on detergent lysis of bacteria and ultracentrifugation. The isolated protein complex can be applied for biochemical and transmission electron microscopy analysis.