Scientists finally cracked how bacteria's spinning motor actually works
After 50 years of research, scientists have uncovered how the bacterial flagellar motor works, confirming a long-standing theory that proton flow drives its rotation. The motor operates using a proton gradient across the cell membrane, with protons moving through stator rings to power the spinning of the flagellum. It can also reverse direction when bacteria detect unfavorable conditions, prompting a change in movement. This discovery resolves a major question in molecular biology and challenges arguments of 'irreducible complexity.'
- ▪The bacterial flagellar motor is powered by a proton gradient, known as the proton motive force, first proposed by Peter Mitchell in 1961.
- ▪Cryo-EM studies since 2020 revealed that protons flow through stator rings at over 2,000 per second, driving rotation of the C ring and flagellum.
- ▪The motor can reverse when phosphorylated CheY molecules bind to the C ring, causing bacteria to tumble and reorient in response to environmental cues.
- ▪Peter Mitchell received the Nobel Prize in 1978 for his proton motive force theory, which was once met with skepticism.
- ▪The finding undermines creationist arguments that the flagellar motor is too complex to have evolved gradually.
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Scientists finally cracked how bacteria's spinning motor actually works Ellsworth Toohey 10:29 am Tue Apr 28, 2026 NatalieIme/shutterstock.com Mike Manson has spent 50 years at Texas A&M studying the bacterial flagellar motor — a molecular machine that spins hundreds of times per second, outpacing a race car's spinning crankshaft, to drive bacteria through water. He finally understands it. "My lifelong quest is now fulfilled," he told Quanta Magazine. "I finally understand how this thing I've been studying for 50 years actually works." The mechanism hinges on an idea that Peter Mitchell published in 1961 and spent years defending against ridicule.
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