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Scientists discover how proteins form crystals that tile a microbe's shell

Date:
December 18, 2019
Source:
DOE/SLAC National Accelerator Laboratory
Summary:
Many microbes wear beautifully patterned crystalline shells, which protect them from a harsh world and can even help them reel in food. Now scientists have zoomed in on the very first step in microbial shell-building: nucleation, where squiggly proteins crystallize into sturdy building blocks. What they found helps explain how the shells assemble themselves so quickly.
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Many microbes wear beautifully patterned crystalline shells, which protect them from a harsh world and can even help them reel in food. Studies at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University have revealed this food-reeling process and shown how shells assemble themselves from protein building blocks.

Now the same team has zoomed in on the very first step in microbial shell-building: nucleation, where squiggly proteins crystallize into sturdy building blocks, much like rock candy crystallizes around a string dipped into sugar syrup.

The results, published today in the Proceedings of the National Academy of Sciences, could shed light on how the shells help microbes interact with other organisms and with their environments, and also help scientists design self-assembling nanostructures for various tasks.

Jonathan Herrmann, a graduate student in Professor Soichi Wakatsuki's group at SLAC and Stanford, collaborated with the structural molecular biology team at SLAC's Stanford Synchrotron Radiation Lightsource (SSRL) on the study. They scattered a powerful beam of X-rays off protein molecules that were floating in a solution to see how the atomic structures of the molecules changed as they nucleated into crystals. Meanwhile, other researchers made a series of cryogenic electron microscope (cryo-EM) images at various points in the nucleation process to show what happened over time.

They found out that crystal formation takes place in two steps: One end of the protein molecule nucleates into crystal while the other end, called the N-terminus, continues to wiggle around. Then the N-terminus joins in, and the crystallization is complete. Far from being a laggard, the N-terminus actually speeds up the initial nucleation step - although exactly how it does this is still unknown, the researchers said -- and this helps explain why microbial shells can form so quickly and efficiently.


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Materials provided by DOE/SLAC National Accelerator Laboratory. Note: Content may be edited for style and length.


Journal Reference:

  1. Jonathan Herrmann, Po-Nan Li, Fatemeh Jabbarpour, Anson C. K. Chan, Ivan Rajkovic, Tsutomu Matsui, Lucy Shapiro, John Smit, Thomas M. Weiss, Michael E. P. Murphy, Soichi Wakatsuki. A bacterial surface layer protein exploits multistep crystallization for rapid self-assembly. Proceedings of the National Academy of Sciences, 2019; 201909798 DOI: 10.1073/pnas.1909798116

Cite This Page:

DOE/SLAC National Accelerator Laboratory. "Scientists discover how proteins form crystals that tile a microbe's shell." ScienceDaily. ScienceDaily, 18 December 2019. <www.sciencedaily.com/releases/2019/12/191218090218.htm>.
DOE/SLAC National Accelerator Laboratory. (2019, December 18). Scientists discover how proteins form crystals that tile a microbe's shell. ScienceDaily. Retrieved October 31, 2024 from www.sciencedaily.com/releases/2019/12/191218090218.htm
DOE/SLAC National Accelerator Laboratory. "Scientists discover how proteins form crystals that tile a microbe's shell." ScienceDaily. www.sciencedaily.com/releases/2019/12/191218090218.htm (accessed October 31, 2024).

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