[VIDEO] Our first ever look at bacterial organelle shells

  • Jun 23, 2017
  • Kerfeld lab, green solutions
  • Department of Energy Projects, Green Solutions (Applied)
  • By Igor Houwat, Layne Cameron, Markus Sutter

Remember when, in biology class, we were taught that animal and plant cells had little organelles in them – like chloroplasts or mitochondria – and bacteria lacked those? And how that fact made bacteria feel a bit less special?

It turns out bacteria have their own counterparts, called bacterial microcompartments (or BMCs for short).

And, in a feat that took about two years to accomplish, Cheryl Kerfeld and her lab have seen the fine details of the shells that make up these bacterial organelles, which function as the organisms’ nano-factories.

The results, led by Michigan State University are featured in the current issue of Science.

“We’ve produced a detailed snapshot – at atomic-level resolution – of the membrane of bacterial organelles,” says Cheryl Kerfeld the Hannah Distinguished Professor of Structural Bioengineering at the MSU-DOE Plant Research Lab. “By seeing the intact bacterial organelle shell, we now understand how the basic building blocks are put together to construct the organelle membrane.”

Markus Sutter, co-author says, “It is like you see something kind of blurry. You put glasses on, and then you see it all clear. This is really exciting. This is what we have been looking to do for years.”

The structure described is likely to become the textbook model of the membrane of primitive bacterial organelles, Kerfeld says.

GIF of the bacterial shell
A GIF of the bacterial microcompartment.
Source: Markus Sutter

Why this is important: BMCs for nanotechnologies

While plant and animal cell organelles are made of  lipids (small molecules found in fats, oils, and waxes), BMCs are made of different types of  proteins.

BMCs are used differently across a diverse range of bacteria. Some pathogenic bacteria use them to outcompete “good” bacteria, while others use BMCs to create energy compounds through  photosynthesis.

But the protein shells that make up BMCs are fundamentally the same. And now that Kerfeld and her team can see a BMC structure, it makes it easier to understand how BMCs work and target them for medical or renewable energy applications.

The structure described is likely to become the textbook model of the membrane of primitive bacterial organelles.

“Our results provide the structural basis to design experiments to explain how molecules cross the organelle shell, how specific  enzymes are targeted to the inside and how the shells self-assemble,” said Kerfeld, who’s also an affiliate of Lawrence Berkeley National Laboratory.

“This work also provides the foundation to develop therapeutics to disrupt the assembly and function of the BMCs found in pathogens or enhance those that play a role in photosynthesis in order to make fuel molecules, rubber, or plastic.”

For more, check out the original story on MSU Today by Layne Cameron.

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