Attempt to explain the assembly of the bacterial flagellum, “a complex process involving more than 70 genes”

_{Denyse O'Leary

April 27, 2018

Intelligent Design, Irreducible Complexity}

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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.

Comments

Richard Dawkins- smartest man in the world who couldn't support the claims of his position if his life depended on it. He is so smart he can't produce any testable hypotheses for his proposed mechanisms. All he can do is try to shift the burden to those who disagree with him. Anyone who accepts evolutionism is smart. ET

ET @2: Instead we have the monumental fraud of a Richard Dawkins, held up to be the "smartest Man in the world" who acknowledges the obvious many, many designs in nature, and yet claims them to be mere illusions and appearances of design. Worse, he has taught this fraud to millions of willing minds over the years. He knows better, but his ideology prevents him from acknowledging Design ... let alone Intelligent Design ... let alone an Intelligent Designer ... let alone God. ayearningforpublius

Their textbooks elucidate the structure of cells. That is something Darwin didn't know anything about. ET

ET,
...what today’s high school biology students know
What do high school students know about this? Do their textbooks show what we are discussing here? OLV

I'm telling you that had Darwin known what was in the black box he would have NEVER came up with his concept of natural selection as a designer mimic. He would have been laughed out of England had people known what today's high school biology students know. ET

Very interesting. Thanks for posting it here.
The bacterial flagellum is a supramolecular motility machine. Flagellar assembly begins with the basal body, followed by the hook and finally the filament. A carboxyl-terminal cytoplasmic domain of FlhA (FlhAC) forms a nonameric ring structure in the flagellar type III protein export apparatus and coordinates flagellar protein export with assembly. However, the mechanism of this process remains unknown.

These results suggest that the flagellar type III export gate complex containing FlhA(L401A) requires FliH and FliI to transport filament-type proteins upon completion of the hook structure. Therefore, we propose that FliH and FliI may support efficient interaction between FliJ and FlhAL to induce structural remodeling of the FlhAC ring structure through cooperative interactions between FlhAL-C of each subunit and FlhAC of its neighboring subunit for the substrate specificity switching of the flagellar protein export apparatus.
Doesn't this seem more irreducible complex than it was thought? Friendly advice to the neo-Darwinian folks: change party affiliation or club membership before it gets more embarrassing. :) The full text of the source paper is available both online and as a downloadable PDF document: Full text PDF OLV

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