Researchers in the US and UK say they have unlocked the secrets of the flexible coils that let urinary tract infections “survive and thrive”, potentially paving the way for new treatments.
The research has revealed the spring-like shock absorber used by the most common cause of UTIs to survive and withstand the tremendous forces of urine flow, where other bacteria cannot.
“We can now generate views of these pili at very high resolution, yielding unprecedented atomic details”
By better understanding how they anchor themselves to the urinary tract lining, scientists will be able to devise new drugs and vaccines to stop UTIs, said the authors of the study.
The bacterium, a form of E. coli, is responsible for up to 90% of UTIs. It lashes itself to the urinary tract lining using appendages, known as pili, which are coiled tightly like a spring.
When enduring the fierce currents of urine flow, the coiled pili flex and bend like an old-fashioned telephone cord, letting the bacteria withstand their equivalent of a tremendous hurricane.
Dr Edward Egelman, from the University of Virginia School of Medicine, said: “It doesn’t just bend, it completely uncoils, and that’s how it can survive these very large forces without breaking. That’s what we were able to show in atomic detail.”
He has collaborated with colleagues at the Institute of Structural and Molecular Biology, run jointly by University College London and Birkbeck College, to produce the most detailed depiction of the pili ever assembled.
“If these pili aren’t assembled, then these bugs aren’t infective at all”
The London researchers performed sub-microscopic imaging using a powerful cryo-electron microscope that allows scientists to investigate and visualize the structure of individual cells and bio-molecules.
Fellow researcher Dr Gabriel Waksman said: “These pili are important surface-exposed appendages that bacteria use to recognise and adhere to host tissues. They are also important in making bacterial biofilms.
“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,” he said.
He added: “We can now generate views of these pili at very high resolution, yielding unprecedented atomic details that shed light into the function of these pili.”
Understanding the shape and structure of the pili is a “key step toward” producing ways to block the bacteria from “getting a toehold in the urinary tract”, suggested the researchers.
“These pili are absolutely essential for the infectivity, because it’s the pili that attach very strongly to the lining of the urinary tract,” Dr Egelman noted. “
“If these pili aren’t assembled, then these bugs aren’t infective at all. They’d wash right out,” he added.