Many bacteria are equipped with a flagellum, a helical propeller that allows bacteria to travel. The flagellum is assembled in a highly organized manner involving the stepwise addition of each of its internal parts. However, there are many open questions as to how this orderly construction is achieved. In a study published in Science Advances, a Japanese research team centered at Osaka University has uncovered new molecular details and provided a model explaining how stepwise flagellar assembly occurs.
As single-celled organisms, bacteria have devised elegant methods to move around their environment. The flagellum consists of a microscopic motor, which provides torque, and a long, rigid, spiral-shaped filament that drives propulsion. The motor and filament are connected by a flexible hook, which allows the bacteria to “steer.” Much like any other motor, the parts of the flagellum have to be put together in exactly the right order.
“Flagellar assembly is a complex process involving more than 70 genes,” lead author Naoya Terahara explains. “First, the basal motor is assembled, followed by the hook, and finally the helical filament. Each structure is built by sending a unique set of proteins to the site of assembly. The cell can somehow sense when each structure is complete, triggering a switch to export the next series of proteins. We wanted to develop a more detailed picture of how this switching occurs.” More.
Okay. And this all just happened to come about by natural selection acting on random mutation? Like War and Peace or The Lord of the Rings?
Great graphics. Paper. (open access)
Authors: Naoya Terahara, Yumi Inoue, Noriyuki Kodera, Yusuke V. Morimoto, Takayuki Uchihashi, Katsumi Imada, Toshio Ando, Keiichi Namba, Tohru Minamino. Insight into structural remodeling of the FlhA ring responsible for bacterial flagellar type III protein export. Science Advances, 2018; 4 (4): eaao7054 DOI: 10.1126/sciadv.aao7054
See also: Flagellum gives bacteria a sense of touch
Hat tip: Oscillations blog, a good source for leading-edge concepts in evolution.