Adhesins from pathogenic bacteria are essential molecules to initiate the infection process, as they allow the bacterium to adhere to the surface of the host cell. Therefore, understanding how they work could facilitate the development of antibacterial drugs with a different mechanism of action than antibiotics, thus allowing the fight against resistant bacteria. These studies could also provide clues to combat viral infections, as the cellular adhesion mechanism of some viruses bears significant similarities to that of bacteria.
This is one of the conclusions of a review work published in the journal Trends in Microbiology, whose main authors are David Aparicio, of the Institute of Molecular Biology of Barcelona of the CSIC and Oscar Quijada, from the Parc Taulí Research and Innovation Institute (I3PT). The article covers research led by scientists from both centers and in which scientists from the UAB and the University of Southern Denmark (SDU) in Denmark have also participated.
Deciphered the mechanism of adhesion to the cell
This team has collaborated for years to understand the mechanism of adhesion of two human pathogenic bacteria: Mycoplasma genitalium, causing various pathologies of the urogenital tract, i Mycoplasma pneumoniae, causing up to 40% of atypical primary pneumonias. "The study of the structure of their proteins allows us to analyze how these bacteria interact with the host and escape the immune system," he says. Sergio Torres (SDU).
Scientists have managed to decipher the three-dimensional structure of proteins by which bacteria adhere to cells to initiate infection. The proteins under study are adhesins, which bind to cellular receptors, sialic acids. In the case of M pneumoniae, this process is carried out by the complex formed by adhesins P1 and P40 / P90, and in the case of M. genitalium, the complex formed by adhesins P110 and P140. “The information provided in this article gives a broad perspective of the functions that the adhesins of M. genitalium and M. pneumoniae", Explain David Vizarraga (IBMB-CSIC).
The structure of the complexes changes, alternating from an "open" state to a "closed" state, which allows the bacterium to adhere and be fixed on the cell or, instead, to detach and slide. on the cell membrane. "Knowledge of these structures would allow the development of new pharmacological strategies based on identifying molecules capable of blocking the binding site of adhesins to human receptors, sialic acids, and thus be able to stop the adhesion of the pathogen during infection." , scientists say.
Bacteria and viruses could use similar mechanisms
The similarities between the adhesion complexes of M. genitalium and M. pneumoniae indicate that they possibly have a common evolutionary origin. Interestingly, the authors of the work say, these complexes bear a striking resemblance to key viral proteins for infection, suggesting that both bacteria and viruses may be using closely related adhesion mechanisms both functionally and evolutionarily.
In addition, the variations identified in the adhesion complexes possibly confer on the bacteria the ability to colonize different tissues of the organism. This is important because, often, the severity of the disease depends on the exact place where the infection occurs. In this regard, the most severe symptoms associated with infections are M pneumoniae have been linked to the spread of the bacterium outside the lungs. Therefore, compressing how variations in adhesins determine or alter the site of infection can help improve the diagnosis and prevention of complicated infections.
Leave a Reply