Scientists have mapped in unprecedented detail the structure of Vibrio bacteria, which can cause life-threatening infections linked to antibiotic resistance.
The King's College London team behind the study, published in Nature Communications, say the finding could provide new targets for life-saving treatment.
The new study comes as infections caused by Vibrio bacteria are an increasing global concern. Cholera is responsible for thousands of deaths a year, and Vibriosis - a severe infection increasingly resistant to antibiotics - is on the rise in southern Europe and the southern coast of the US, where the bacteria thrives in warm, coastal waters.
Understanding these dangerous bacteria at this level of detail gives us the best chance to develop targeted interventions to stop them from causing severe infections
Dr Julien Bergeron at the Faculty of Life Sciences & Medicine
Many types of bacteria have what's called a flagellum, which the team describe as a microscopic "propeller". It is essential for swimming and is what allows bacteria to infiltrate a person's - their host's - bloodstream, leading to severe infection.
In Vibrio species, this flagellum is surrounded by a sheath, a membrane-like shield that protects the bacterium from the host's immune system. Targeting this sheath at a molecular level offers a promising new treatment approach not tried before.
Rather than killing the bacteria outright - as would be the tactic of antibiotics - impairing the flagellum or its sheath could stop them from being able to cause infection, with the additional benefit of reducing the pressure for bacteria to develop antibiotic resistance.
Swimming is essential for many pathogens to colonize their host. In Vibrio, the sheath protects the bacterium from being found and killed by the immune system, making these types of infections particularly hard to fight.By revealing the architecture of this system at atomic resolution, we can now see how the flagellum rotates within the sheath and how this protective layer is assembled.
Dr Julien Bergeron
To understand this mechanism in detail, researchers used one of the world's most powerful cryo-electron microscopes - a hallmark technique in their studies of bacterial pathogens - to visualize the sheathed flagellum at atomic resolution.
This revealed details of how the flagellum rotates within the sheath and suggests a mechanism for the formation of this sheath.
We believe that interfering with the sheath or the mechanisms enabling high-speed rotation could prevent Vibrio from colonising hosts, or could expose the flagellum to a successful immune attack.These findings represent a critical step toward developing new treatments against Cholera and Vibriosis, including the most dangerous antibiotic-resistant strains.
Kailin Qin, PhD student and co-author of the study
