Animalcules and Their Motors
8 days ago
- #cryo-electron microscopy
- #flagella
- #microbiology
- Antoni van Leeuwenhoek first observed microbes in motion in 1674, calling them 'animalcules'.
- Christian Gottfried Ehrenberg later identified flagella in the 1830s, but their mechanism remained unknown until the 20th century.
- Flagella are composed of four parts: basal body, stators, flexible hook, and tail, with the tail spinning like a corkscrew to propel the cell.
- Different bacteria have evolved flagella optimized for their environments, such as E. coli for speed and Campylobacter jejuni for torque in viscous environments.
- Recent advances in cryo-electron microscopy have revealed detailed structures of flagellar motors, including the high-torque motor of C. jejuni.
- Flagella self-assemble from hundreds of interlocking proteins, with each protein finding its place in the growing structure.
- The flagellum is powered by proton flow across the cell membrane, not ATP, with stators converting this flow into mechanical rotation.
- C. jejuni's flagellar motor has 17 stators positioned further from the central driveshaft, providing three times the torque of E. coli.
- Flagella have evolved independently in bacteria, archaea, and eukaryotes, solving the fundamental problem of cell locomotion.
- The study of flagella continues to reveal the molecular mechanisms behind Leeuwenhoek's early observations of microbial movement.