Cholera kills around 95,000 people each year and is caused by the bacterium Vibrio cholerae, which infects cells in the small intestine. The bacteria use flagella—tail-like structures—to move and reach those cells. Scientists have known the proteins that make these flagella for decades, but how the pieces fit together remained unclear.
Yale School of Medicine researchers reported new findings in Nature Microbiology that reveal the molecular structure of flagella in live V. cholerae. Jun Liu was the senior author and Wangbiao Guo was the first author. The team developed a microscopy approach to view the flagella while the bacteria were alive. Guo and a collaborator made mutated bacteria whose flagella proteins were designed to light up, then froze the cells in liquid ethane and imaged them with a powerful electron microscope at near-atomic resolution.
The images showed how each of four flagella proteins fits inside a hydrophilic protective sheath, which had blocked earlier studies. The sheath may act like a lubricant, allowing the flagellum to rotate independently from the outer casing. This slippery system could help V. cholerae move faster through liquid and push past the mucus layer to infect cells. Liu said the techniques could lead to new drugs that target flagella.
Difficult words
- cholera — a severe infectious disease that causes diarrhea
- bacterium — a single microscopic organism that can cause disease
- flagellum — a tail-like structure that helps movementflagella
- microscopy — techniques to make tiny things visible with instruments
- mutate — to change genes so characteristics are differentmutated
- hydrophilic — attracted to water or able to mix with water
- sheath — a protective covering around something
- lubricant — a substance that reduces friction between surfaces
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Do you think drugs that stop flagella movement could reduce cholera infections? Why or why not?
- What are the benefits of using advanced microscopes to study bacteria? Give one or two reasons.
- Have you used a microscope at school or work? How did it help you understand small things?
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