Salmonella and many other bacterial pathogens use a nano syringe–like device to deliver toxic proteins into target human cells. Now scientists at Yale and University of Texas Medical School–Houston have used cryo–electron tomography to reveal the molecular structure of this device, which is about 1/1000th the width of a human hair.

The nano–syringe, called Type III protein secretion machine, features an injection point at one end and a sort of staging area at the bottom, where proteins are selected and sorted for delivery into target cells.

“The device is like a stinger and injects ready–made bacterial proteins into mammalian cells to commandeer them for the benefit of the pathogen,” said Jorge Galan, the Lucille P. Markey Professor of Microbial Pathogenesis and co–senior author of the paper.

Knowledge of the structure could help researchers devise new anti–infective strategies against a variety of bacterial pathogens such as Salmonella, Pseudomonas, Escherichia coli, Yersinia pestis, and Chlamydia.

The research was published March 9 in the journal Cell.