Forum for Science, Industry and Business

Team discovers how bacteria resist a 'Trojan horse' antibiotic

But microbes also must protect themselves from their own toxins. The defenses they employ for protection can be acquired by other species, leading to antibiotic resistance.

The researchers focused on an enzyme, known as MccF, that they knew could disable a potent “Trojan horse” antibiotic that sneaks into cells disguised as a tasty protein meal. The bacterial antibiotic, called microcin C7 (McC7) is similar to a class of drugs used to treat bacterial infections of the skin.

“How Trojan horse antibiotics work is that the antibiotic portion is coupled to something that’s fairly innocuous – in this case it’s a peptide,” said University of Illinois biochemistry professor Satish Nair, who led the study. “So susceptible bacteria see this peptide, think of it as food and internalize it.”

The meal comes at a price, however: Once the bacterial enzymes chew up the amino acid disguise, the liberated antibiotic is free to attack a key component of protein synthesis in the bacterium, Nair said.

“That is why the organisms that make this thing have to protect themselves,” he said.

In previous studies, researchers had found the genes that protect some bacteria from this class of antibiotic toxins, but they didn’t know how they worked. These genes code for peptidases, which normally chew up proteins (polypeptides) and lack the ability to recognize anything else.

Before the new study, “it wasn’t clear how a peptidase could destroy an antibiotic,” Nair said.

To get a fuller picture of the structure of the peptidase, Illinois graduate student Vinayak Agarwal crystallized MccF while it was bound to other molecules, including the antibiotic. An analysis of the structure and its interaction with the antibiotic revealed that MccF looked a lot like other enzymes in its family, but with a twist – or, rather, a loop. Somehow MccF has picked up an additional loop of amino acids that it uses to recognize the antibiotic, rendering it ineffective.

“Now we know that specific amino acid residues in this loop are responsible for making this from a normal housekeeping gene into something that’s capable of degrading this class of antibiotics,” Nair said.

Nair also is an affiliate of the Center for Biophysics and Computational Biology, the department of chemistry and of the Institute for Genomic Biology at Illinois. The research team included scientists from the Russian Academy of Sciences and Rutgers University.

Diana Yates | University of Illinois
Further information:
http://www.illinois.edu

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...