Science News: Bacteria Armored with Tiny Tori

Take a close look at this image from the June 2012 edition of the science journal Nature.

S-layer bacteria
©VIB, 2012

The image depicts the bacterium Geobacillus stearothermophilus, with a molecular-level resolution of the structure of its protective coat of mail. Do you see that the protective S-layer consists of interlocked tori? The article states how incredibly stable this toroidal crystalline structure appears to be.

From the VIB press release, 11June2012:

With the publication of their findings in Nature, VIB researchers Han Remaut and Ekaterina Baranova at the Vrije Universiteit Brussel, together with French and British scientists, have pulled the hitherto unknown S layer out of obscurity. "We succeeded in imaging the structure of the protein coat for one specific bacterium (Geobacillus stearothermophilus) down to its individual atoms," says Han Remaut. "We were also able to determine how the individual proteins attached to each other to form a 2D structure similar to a kind of chainmail from the Middle Ages, but on a molecular scale, of course." ........
... To what extent the protein coat plays a role in disease processes in humans still needs to be determined by the Brussels researchers. The S-layer they imaged was that of a harmless soil bacterium. Some pathogenic bacteria, such as those that cause anthrax (Bacillus anthracis) or the hospital bug Clostridium difficile, also feature this type of armor. “There are indications that these bacteria use their S-layer for attaching to the cells of the host. But whether the S-layer forms a potential starting point for fighting these bacteria is still unclear," adds Remaut. “That will require more research."

Interface with nanotechnology
Remaut's research is also being followed with interest by chemists, nanotechnologists and material scientists. The 2D-structure and mechanisms underlying the development of the S-layer makes it suitable as a component or as a model for new nanomaterials. In particular, the self-assembly of the S-layer fascinates scientists. "You can compare this self-assembly to a pile of bricks organizing themselves into a perfectly laid wall, but on a nanoscale – one-billionth the size of a common brick," says Remaut. “Such artificial miniature structures could be used, for example, for efficiently delivering active ingredients, such as drugs, to places in the body that are hard to reach."

This is an excellent example of how fundamental biology research can be a source of inspiration for the development of future nanomaterials.

Scientific publication
The research will be published in the leading journal Nature (SbsB structure and lattice reconstruction unveil Ca21 triggered S-layer assembly), Doi 10.1038/nature11155.