Bacterial motors carefully studied:flagellum complexity (Introduction)

by David Turell , Wednesday, November 16, 2016, 21:09 (2928 days ago) @ David Turell

A very careful study which shows the various protein molecules that make up a flagellum. Since this provides motility, when the organism appeared this had to be an initial part:

http://www.nature.com/articles/ncomms13425#f2

Abstract: "The bacterial flagellar hook is a tubular helical structure made by the polymerization of multiple copies of a protein, FlgE. Here we report the structure of the hook from Campylobacter jejuni by cryo-electron microscopy at a resolution of 3.5 Å. On the basis of this structure, we show that the hook is stabilized by intricate inter-molecular interactions between FlgE molecules. Extra domains in FlgE, found only in Campylobacter and in related bacteria, bring more stability and robustness to the hook. Functional experiments suggest that Campylobacter requires an unusually strong hook to swim without its flagella being torn off. This structure reveals details of the quaternary organization of the hook that consists of 11 protofilaments. Previous study of the flagellar filament of Campylobacter by electron microscopy showed its quaternary structure made of seven protofilaments. Therefore, this study puts in evidence the difference between the quaternary structures of a bacterial filament and its hook."

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"Flagella are found in both gram-positive and gram-negative bacteria. Although flagellar hooks appear identical at first sight, the diversity of flagellar hook proteins suggests that the hooks have diverged to specifically fit the motility requirements of each bacterium.

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"Flagella, although macroscopically similar, have evolved features that will make them specially adapted to particular tasks. The intestinal jejunum is a viscous environment where C. jejuni is adapted for swimming25,26. The results shown here tend to support the idea that additional strengthening of the hook in C. jejuni is necessary to enable motility in this viscous environment."

Comment: Please look at the diagrams and illustrations in the article. That is the easiest way to understand the enormous complexity of this bacterial motor. Bacteria did not self-invent these motors. That is self-evident.