Staphylococcus aureus attack strategy cracked by researchers

Ecole Polytechnique Fédérale de Lausanne (EPFL) deciphered the attack strategy of bacteria such as Staphylococcus aureus.

They found that some bacteria, including Staphylococcus aureus, has the ability to deploy tiny darts which kills the host cell by piercing the membrane.

The approach would have the advantage of not causing mutations, which lead to resistance in pathogenic bacteria, say the researchers.

Bacteria weaponry​

The concept is to address the weaponry of the bacteria rather than the bacteria itself, which is attractive at a time when multiple antibiotic resistances are becoming increasingly common.

Matteo Dal Peraro et al found an assembly of proteins that, in unfolding at the right time, takes the form of a spur.

To attack the host cell, the weapon must attach and on the surface of the aggressor is a mechanism composed of seven proteins that are folded over and assembled into a ring.

Researchers were able to show how these long molecules unfold to form a kind of spur.

Foodborne impact​

Staphylococcus aureus has the ability to make seven different toxins that are frequently responsible for food poisoning, according to the US Centers for Disease Control and Prevention (CDC).

The most common way for food to be contaminated is through contact with food workers who carry the bacteria or through contaminated milk and cheeses, said the agency.

EPFL researchers worked on strains of Aeromonas hydrophila​, a bacterium of which some strains are capable of causing gastroenteritis and other infections in humans, said the FDA.

The foodborne form of the illness results from ingestion of the organism (from animal origin, seafood, or produce) or water.

Peptide is the trigger or a small organic molecule, which when exposed to the enzymes of the host organism, it detaches.

The balance of the assembly adjusts: the proteins adopt a new form, spreading out in a circular motion to form a spur, which then pierces the membrane of the host cell, said the researchers.

In Petri dishes the researchers could cause the formation of these darts, exposing microorganisms to digestive enzymes. They were able to model precisely how each protein dynamically rearranges, once the peptide is missing, to form the spur.

Source: Nature Chemical Biology

Online ahead of print, DOI: 10.1038/nchembio.1312​

“Molecular assembly of the aerolysin pore Reveals a swirling membrane insertion mechanism”​

Authors: Matteo Degiacomi, Ioan Iacovache, Lucile Pernot, Mohamed Chami, Misha Kudryashev,Henning Stahlberg, F Gisou van der Goot and Matteo Dal Peraro