Protective antibiotic in breast milk

Graz researchers investigate protein molecule lactoferricin from breast milk

05/15/2014

If dangerous germs occur, resistance to the antibiotics used so far is becoming more common. Accordingly, research is in full swing to develop new strategies to continue to fight persistent pathogens. In this context, scientists from Graz have dealt with the protein molecule lactoferricin found in breast milk in an EU project - and have now been able to decipher how the peptide works and how it can be enhanced in its mode of action. Accordingly, the current study could make an important contribution to the development of innovative antibiotics, according to the Communication of the Karl-Franzens-University Graz.

Breastfeeding brings many benefits
There are several advantages to having mothers breastfeeding: vials do not need to be disinfected, milk powder should not be shopped and mixed several times a day, and it is not necessary to bring the milk to the right temperature for each meal. Instead, the baby can basically be fed at any time and place as needed. In addition to these practical aspects, breastmilk has another decisive advantage over substitute nutrition - because it contains all the ingredients that are important for the development of the child in the right dose, such as carbohydrates or lipid-splitting enzymes from the outset.

Protein molecules in the defense against bacteria advantageous against antibiotics
Protein from breast milk, which is considered a guarantor of the natural immune defense, also plays an important role. One of these small proteins is the peptide „lactoferricin“, which has a strong effect: „In-body peptides - small protein molecules - have an advantage over conventional antibiotics in the defense against bacteria: they act directly and quickly on the cell membrane, the envelope of the bacterium, and destroy it, even before resistance can form“, explains Ass.-Prof. Dr. Dagmar Zweytick from the Institute of Molecular Biosciences of the Karl-Franzens-University Graz.

Researchers are changing the amino acid sequence of lactoferricin
Although lactoferricin is found in natural breast milk, it is too weak to successfully fight serious infections. In order to increase its effectiveness, a research team from the University of Graz, in cooperation with colleagues from the Universities of Ljubljana and Houston, Texas, modified lactoferricin, thus enhancing the natural antibacterial activity and decoding the mode of action of the small molecule. As the researchers currently in the journal „PLOS ONE“ As part of the project, the amino acid sequence of lactoferricin was first modified and a so-called „fatty acid chain“ attached (acylation). Subsequent studies showed a strong effect, as both the acylated and the non-acylated variants were now able to severely damage the cell membrane of the bacterium Escherichia coli - which was used as a model organism. „The positively charged peptides dock with and break down the negatively charged lipids of the bacterial cell membrane. In addition, the acylated peptides also disrupt cell division and thus the proliferation of bacteria. The peptide variants have already been internationally patented“, explain the researchers of the University of Graz.

Study should help to clarify complex mechanisms of action
With their work, researchers may have made an important contribution to future antibiotic research: „In summary, N-acylated peptides, in addition to killing bacteria by severely damaging the membrane, can interact with bacterial lipids in a manner that directly or indirectly causes deficiencies in cell division. [...] The study should help to clarify the manifold mechanisms by which antimicrobial peptides can act on bacterial membranes in order to improve the peptide activity and specificity“, so the scientists in their article. (No)