The Loh Down On Science

Bacterial Gunslingers

Dart-gun enthusiasts? This one's for you!

This is Sandra Tsing Loh with the Loh Down on Science, and a spring-loaded gun that fires poison darts.

Poison? So, not a Nerf product, then.

No ... this one's a spring-loaded cellular gun that fires molecular darts ... in bacteria.

Called the Type-Six Secretion System, or T6SS, it was discovered a few years ago by the lab of Harvard microbiologist John Mekalanos.

Recently, Caltech structural biologist Grant Jensen teamed up with Mekalanos to find out how the T6SS works in cholera bacteria.

The team used a technique called cryo-tomography, in which videos are created from still electron-microscope images. And they saw the whole process at work.

Within just tens of seconds, a helical tube forms around a toxic molecule inside the bacteria. The tube then contracts, forcing the "dart" out--and potentially into an enemy cell. Then the tube disassembles.

The team doesn't yet know what makes the bacterial gun load and lock, but they saw up to five per cell operating at once.

Still, don't expect them at Toys "R" Us anytime soon. Poison.



The Loh Down on Science, online, at lohdown.org. Produced by 89.3 KPCC and the California Institute of Technology, and made possible by TIAA-CREF.

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