Exposed: bacteria coils that resist urine flow


Rebecca Pool

Friday, January 15, 2016 - 14:00
Cryo-EM image: Flexible coils allow bacteria to withstand urine flow. [UVA Health System]
Using cryo-electron microscopy, researchers have revealed the atomic structure of coil-like pili in E Coli bacteria, that help urinary tract infections survive the tremendous force of urine flow.
Image: Understanding the coils' structure will help researchers find ways to prevent UTIs. [UVA Health System]
To produce the most detailed depiction of the pili ever assembled, Professor Edward Egelman from the University of Virgina, Professor Gabriel Waksman from UCL and Birkbeck College, and colleagues turned to cryo-EM at Diamond Light Source, UK.
E coli latch onto the lining of the urinary tract using pili, which comprise a short tip fibrillum mounted on a 1–2 μM long and helically wound rod.
As Waksman highlights: "Until recently, there was no method to determine the atomic-resolution details of these appendages. However, recently, revolutionary progress in electron microscopy has changed that."
Video: UVA's Edward Egelman discusses the UTI research and displays a video of the coils.
Using a Titan Krios, the researchers solved the 3.8 Å resolution structure of the rod, reconstructing atomic models that provide clues to the rod’s remarkable mechanical properties and will allow researchers to design drugs to prevent infection.
"These pili are important surface-exposed appendages that bacteria use to recognize and adhere to host tissues," says Waksman. "The rod has striking spring-like properties, being able to uncoil and recoil depending on the intensity of shear forces generated by urine flow."
"These pili are absolutely essential for the infectivity, because it's the pili that attach very strongly to the lining of the urinary tract," adds Egelman. "If these pili aren't assembled, then these bugs aren't infective at all. They'd wash right out."
Research is published in Cell.
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