Salmonella type III effector SopB modulates host cell exocytosis

Area of Science:

• Microbiology
• Cell Biology
• Infectious Diseases

Background:

• Salmonella enterica pathogenesis relies on intracellular replication within the Salmonella-containing vacuole (SCV).
• Bacterial effectors secreted via type III secretion systems (T3SS-1 and T3SS-2) modify the SCV and interact with host endocytic pathways.

Purpose of the Study:

• To investigate if Salmonella effector proteins interact with the host cell's exocytic pathway.
• To identify specific effectors involved in modulating exocytosis.

Main Methods:

• Secreted alkaline phosphatase (SEAP) assay to screen for effectors inhibiting the secretory pathway.
• Vesicular stomatitis virus glycoprotein-green fluorescent protein (VSVG-GFP) transport assay to confirm blockade of exocytosis.

Main Results:

• Three Salmonella effectors were identified as inhibitors of the secretory pathway using the SEAP assay.
• Salmonella outer protein B (SopB) was confirmed to block exocytosis.
• The 4-phosphatase activity of SopB was essential for its exocytosis-inhibiting function.

Conclusions:

• Salmonella effectors, particularly SopB, can interfere with the host cell's exocytic pathway.
• This interaction may facilitate Salmonella replication by providing nutrients, membrane material for SCV biogenesis, or by altering host immune responses.