New images uncover mysterious structures inside microbes, including mini towers, fishhooks, train tracks and horseshoes
Science News said:On the surface, bacteria may appear bland. But there’s more going on inside than meets the eye, new research is revealing.
For many years, scientists thought that bacteria didn’t have internal structures and were basically “bags of enzymes,” says structural and cell biologist Martin Warren of the University of Kent in England.
Now, one group of researchers has described a rich collection of mysterious structures and compartments within bacteria. No one knows the function of the constructs, the researchers report online June 12 in the Journal of Bacteriology, but they must be important for bacteria to spend so much energy building them.
A different team of scientists presents the first atomic-scale look at a complete bacterial microcompartment in the June 23 Science. Microcompartments are protein shells that bacteria use to keep certain chemical reactions separate from the rest of the cell. Knowing how the microcompartment is assembled could have important applications in biotechnology and medicine, the researchers say.
The two studies demonstrate how complex bacteria really are, says Warren, who wasn’t involved in either. “They’re both fantastic pieces of work. If anybody ever thought microbiology was boring, they should have a look at this.”
Since the 1950s, biologists have known that photosynthetic cyanobacteria make microcompartments, called carboxysomes, which house an important photosynthesis enzyme. About 20 percent of bacteria — even ones that don’t do photosynthesis — have the genes for making similar microcompartments. Many of those tiny chambers appear only when bacteria encounter certain molecules they can use for food. For instance, some pathogenic bacteria form microcompartments to help them digest mucus from people’s intestines, Warren says.
Many researchers have worked to engineer microcompartments to make drugs, industrial chemicals or biofuels. That’s been difficult because scientists didn’t fully understand the structures’ construction. They knew that proteins snapped together to make pentagon- and hexagon-shaped units, but didn’t know how the subunits came together in multi-sided spheres. “It’s like playing with Lego building blocks, but not understanding how the bricks fit together,” says Danielle Tullman-Ercek, a synthetic biologist at Northwestern University in Evanston, Ill.
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