Toxin entry: how bacterial proteins get into mammalian cells

Area of Science:

• Microbiology
• Cell Biology
• Toxicology

Background:

• Certain bacteria produce protein toxins that target mammalian cells.
• These toxins disrupt cellular processes, often causing cell death.
• Toxin activity requires translocation of the catalytic polypeptide into the host cell cytosol.

Purpose of the Study:

• To elucidate the mechanisms by which bacterial protein toxins translocate into mammalian cells.
• To investigate the role of endosomes and the secretory pathway in toxin entry.

Main Methods:

• Analysis of toxin entry pathways following endocytosis.
• Investigation of pH-dependent channel formation in endosomes.
• Characterization of toxin interaction with the endoplasmic reticulum.

Main Results:

• Some toxins utilize acidic endosomal environments to form translocation channels.
• Other toxins are transported via vesicular transport to the endoplasmic reticulum.
• This demonstrates the reversibility of the mammalian cell secretory pathway for toxin entry.

Conclusions:

• Bacterial toxins employ distinct strategies to reach the mammalian cell cytosol.
• Endosomal acidification is a key trigger for translocation for certain toxins.
• The secretory pathway can be exploited by toxins, highlighting its functional reversibility.