Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Team discovers how bacteria resist a 'Trojan horse' antibiotic

20.03.2012
A new study describes how bacteria use a previously unknown means to defeat an antibiotic. The researchers found that the bacteria have modified a common “housekeeping” enzyme in a way that enables the enzyme to recognize and disarm the antibiotic.
The study appears in the Proceedings of the National Academy of Sciences.
Bacteria often engage in chemical warfare with one another, and many antibiotics used in medicine are modeled on the weapons they produce.

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.

With this information, researchers – and eventually, doctors and other clinicians – will be able to scan the genomes of disease-causing bacteria to find out which ones have genes with the antibiotic-resistance loop in them, Nair said. “If we know what type of bacteria are causing an infection we know what kind of antibiotic to give and what kind not to give,” he 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.

Editor’s notes: To reach Satish Nair, call 217-333-0641;
email snair@illinois.edu
The paper, “Structure and Function of a Serine Carboxypeptidase Adapted for Degradation of the Protein Synthesis Antibiotic Microcin C7,” is available online or from the U. of I. News Bureau.

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

More articles from Life Sciences:

nachricht Polarization of Br2 molecule in vanadium oxide cluster cavity and new alkane bromination
13.07.2020 | Kanazawa University

nachricht Researchers present concept for a new technique to study superheavy elements
13.07.2020 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron cryo-microscopy: Using inexpensive technology to produce high-resolution images

Biochemists at Martin Luther University Halle-Wittenberg (MLU) have used a standard electron cryo-microscope to achieve surprisingly good images that are on par with those taken by far more sophisticated equipment. They have succeeded in determining the structure of ferritin almost at the atomic level. Their results were published in the journal "PLOS ONE".

Electron cryo-microscopy has become increasingly important in recent years, especially in shedding light on protein structures. The developers of the new...

Im Focus: The spin state story: Observation of the quantum spin liquid state in novel material

New insight into the spin behavior in an exotic state of matter puts us closer to next-generation spintronic devices

Aside from the deep understanding of the natural world that quantum physics theory offers, scientists worldwide are working tirelessly to bring forth a...

Im Focus: Excitation of robust materials

Kiel physics team observed extremely fast electronic changes in real time in a special material class

In physics, they are currently the subject of intensive research; in electronics, they could enable completely new functions. So-called topological materials...

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

 
Latest News

Black phosphorus-based van der Waals heterostructures for mid-infrared light-emission applications

13.07.2020 | Physics and Astronomy

Polarization of Br2 molecule in vanadium oxide cluster cavity and new alkane bromination

13.07.2020 | Life Sciences

Researchers present concept for a new technique to study superheavy elements

13.07.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>