Shoot Out

Bacteria often use sophisticated weaponry to pump human cells full of toxins. Legionella pneumophila (among other bacterial invaders) use this ‘Type IV secretion system’ to inject their hosts with around 300 molecules per 'shot'. This 3D computer model pieces together clues from electron cryotomography – examining the molecular mechanics in detail – followed by fluorescence microscopy to watch how they assemble and move. With its artificially-coloured red 'barrel' imbedded in a host cell, chambers around the outside of the tiny protein machine help to trigger the release of toxins. Knowing more about how all these mechanisms work together, scientists are developing new antibiotics to specifically disarm these bacterial 'guns' in the fight against Legionnaire’s disease, whooping cough and certain types of cancer.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Video from work by Debnath Ghosal and Kwangcheol C. Jeong, and colleagues
• Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, and Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO, USA
• Image copyright held by Nature Publishing Group 2019; reproduced with permission
• Published in Nature Microbiology, April 2019